[ { "key": "2TMJG5VC", "version": 3, "library": { "type": "group", "id": 157928, "name": "Complex Oxides", "links": { "alternate": { "href": "https://www.zotero.org/groups/complex_oxides", "type": "text/html" } } }, "links": { "self": { "href": "https://api.zotero.org/groups/157928/items/2TMJG5VC", "type": "application/json" }, "alternate": { "href": "https://www.zotero.org/groups/complex_oxides/items/2TMJG5VC", "type": "text/html" } }, "meta": { "createdByUser": { "id": 503034, "username": "tzhang18", "name": "", "links": { "alternate": { "href": "https://www.zotero.org/tzhang18", "type": "text/html" } } }, "creatorSummary": "Zhang et al.", "parsedDate": "2013-03-29", "numChildren": 2 }, "data": { "key": "2TMJG5VC", "version": 3, "itemType": "journalArticle", "title": "Topology-Driven Magnetic Quantum Phase Transition in Topological Insulators", "creators": [ { "creatorType": "author", "firstName": "Jinsong", "lastName": "Zhang" }, { "creatorType": "author", "firstName": "Cui-Zu", "lastName": "Chang" }, { "creatorType": "author", "firstName": "Peizhe", "lastName": "Tang" }, { "creatorType": "author", "firstName": "Zuocheng", "lastName": "Zhang" }, { "creatorType": "author", "firstName": "Xiao", "lastName": "Feng" }, { "creatorType": "author", "firstName": "Kang", "lastName": "Li" }, { "creatorType": "author", "firstName": "Li-li", "lastName": "Wang" }, { "creatorType": "author", "firstName": "Xi", "lastName": "Chen" }, { "creatorType": "author", "firstName": "Chaoxing", "lastName": "Liu" }, { "creatorType": "author", "firstName": "Wenhui", "lastName": "Duan" }, { "creatorType": "author", "firstName": "Ke", "lastName": "He" }, { "creatorType": "author", "firstName": "Qi-Kun", "lastName": "Xue" }, { "creatorType": "author", "firstName": "Xucun", "lastName": "Ma" }, { "creatorType": "author", "firstName": "Yayu", "lastName": "Wang" } ], "abstractNote": "The breaking of time reversal symmetry in topological insulators may create previously unknown quantum effects. We observed a magnetic quantum phase transition in Cr-doped Bi2(SexTe1-x)3 topological insulator films grown by means of molecular beam epitaxy. Across the critical point, a topological quantum phase transition is revealed through both angle-resolved photoemission measurements and density functional theory calculations. We present strong evidence that the bulk band topology is the fundamental driving force for the magnetic quantum phase transition. The tunable topological and magnetic properties in this system are well suited for realizing the exotic topological quantum phenomena in magnetic topological insulators.\nEditor's Summary\nTopological insulators owe their exotic properties to the peculiarities of their band structure, and one can induce a transition between a topologically trivial and nontrivial material by chemical doping. Now, J. Zhang et al. (p. 1582) have gone a step further—simultaneously observing that a magnetic quantum transition as the ratio of Se and Te is varied in Bi2(SexTe1-x)3 thin films grown by molecular beam epitaxy and doped with magnetic Cr. Photoemission and transport experiments, as well as density functional calculations, imply that the topological transition induces magnetism", "publicationTitle": "Science", "publisher": "", "place": "", "date": "03/29/2013", "volume": "339", "issue": "6127", "section": "", "partNumber": "", "partTitle": "", "pages": "1582-1586", "series": "", "seriesTitle": "", "seriesText": "", "journalAbbreviation": "Science", "DOI": "10.1126/science.1230905", "citationKey": "", "url": "http://www.sciencemag.org/content/339/6127/1582", "accessDate": "2013-04-06T06:57:53Z", "PMID": "", "PMCID": "", "ISSN": "0036-8075, 1095-9203", "archive": "", "archiveLocation": "", "shortTitle": "", "language": "en", "libraryCatalog": "www.sciencemag.org", "callNumber": "", "rights": "", "extra": "", "tags": [], "collections": [ "8N65A5JS" ], "relations": {}, "dateAdded": "2013-04-06T06:57:53Z", "dateModified": "2013-04-06T06:57:53Z" } }, { "key": "ZA8FBU7P", "version": 3, "library": { "type": "group", "id": 157928, "name": "Complex Oxides", "links": { "alternate": { "href": "https://www.zotero.org/groups/complex_oxides", "type": "text/html" } } }, "links": { "self": { "href": "https://api.zotero.org/groups/157928/items/ZA8FBU7P", "type": "application/json" }, "alternate": { "href": "https://www.zotero.org/groups/complex_oxides/items/ZA8FBU7P", "type": "text/html" }, "up": { "href": "https://api.zotero.org/groups/157928/items/2TMJG5VC", "type": "application/json" } }, "meta": { "createdByUser": { "id": 503034, "username": "tzhang18", "name": "", "links": { "alternate": { "href": "https://www.zotero.org/tzhang18", "type": "text/html" } } } }, "data": { "key": "ZA8FBU7P", "version": 3, "parentItem": "2TMJG5VC", "itemType": "attachment", "linkMode": "linked_url", "title": "Snapshot", "accessDate": "2013-04-06T06:57:53Z", "url": "http://www.sciencemag.org/content/339/6127/1582.abstract", "note": "", "contentType": "text/html", "charset": "", "tags": [], "relations": {}, "dateAdded": "2013-04-06T06:57:53Z", "dateModified": "2013-04-06T06:57:53Z" } }, { "key": "SN8NHA4U", "version": 3, "library": { "type": "group", "id": 157928, "name": "Complex Oxides", "links": { "alternate": { "href": "https://www.zotero.org/groups/complex_oxides", "type": "text/html" } } }, "links": { "self": { "href": "https://api.zotero.org/groups/157928/items/SN8NHA4U", "type": "application/json" }, "alternate": { "href": "https://www.zotero.org/groups/complex_oxides/items/SN8NHA4U", "type": "text/html" }, "up": { "href": "https://api.zotero.org/groups/157928/items/2TMJG5VC", "type": "application/json" } }, "meta": { "createdByUser": { "id": 503034, "username": "tzhang18", "name": "", "links": { "alternate": { "href": "https://www.zotero.org/tzhang18", "type": "text/html" } } } }, "data": { "key": "SN8NHA4U", "version": 3, "parentItem": "2TMJG5VC", "itemType": "attachment", "linkMode": "linked_url", "title": "Full Text PDF", "accessDate": "2013-04-06T06:57:53Z", "url": "http://www.sciencemag.org/content/339/6127/1582.full.pdf", "note": "", "contentType": "application/pdf", "charset": "", "tags": [], "relations": {}, "dateAdded": "2013-04-06T06:57:53Z", "dateModified": "2013-04-06T06:57:53Z" } }, { "key": "68DQ4EAK", "version": 3, "library": { "type": "group", "id": 157928, "name": "Complex Oxides", "links": { "alternate": { "href": "https://www.zotero.org/groups/complex_oxides", "type": "text/html" } } }, "links": { "self": { "href": "https://api.zotero.org/groups/157928/items/68DQ4EAK", "type": "application/json" }, "alternate": { "href": "https://www.zotero.org/groups/complex_oxides/items/68DQ4EAK", "type": "text/html" } }, "meta": { "createdByUser": { "id": 503034, "username": "tzhang18", "name": "", "links": { "alternate": { "href": "https://www.zotero.org/tzhang18", "type": "text/html" } } }, "creatorSummary": "Cai et al.", "parsedDate": "2012-08-19", "numChildren": 2 }, "data": { "key": "68DQ4EAK", "version": 3, "itemType": "journalArticle", "title": "Visualizing the microscopic coexistence of spin density wave and superconductivity in underdoped NaFe1-xCoxAs", "creators": [ { "creatorType": "author", "firstName": "Peng", "lastName": "Cai" }, { "creatorType": "author", "firstName": "Xiaodong", "lastName": "Zhou" }, { "creatorType": "author", "firstName": "Wei", "lastName": "Ruan" }, { "creatorType": "author", "firstName": "Aifeng", "lastName": "Wang" }, { "creatorType": "author", "firstName": "Xianhui", "lastName": "Chen" }, { "creatorType": "author", "firstName": "Dung-Hai", "lastName": "Lee" }, { "creatorType": "author", "firstName": "Yayu", "lastName": "Wang" } ], "abstractNote": "Although the origin of high temperature superconductivity in the iron pnictides is still under debate, it is widely believed that magnetic interactions or fluctuations play an important role in triggering Cooper pairing. Because of the relevance of magnetism to pairing, the question of whether long range spin magnetic order can coexist with superconductivity microscopically has attracted strong interests. The available experimental methods used to answer this question are either bulk probes or local ones without control of probing position, thus the answers range from mutual exclusion to homogeneous coexistence. To definitively answer this question, here we use scanning tunneling microscopy to investigate the local electronic structure of an underdoped NaFe1-xCoxAs near the spin density wave (SDW) and superconducting (SC) phase boundary. Spatially resolved spectroscopy directly reveal both the SDW and SC gap features at the same atomic location, providing compelling evidence for the microscopic coexistence of the two phases. The strengths of the SDW and SC features are shown to anti correlate with each other, indicating the competition of the two orders. The microscopic coexistence clearly indicates that Cooper pairing occurs when portions of the Fermi surface (FS) are already gapped by the SDW order. The regime TC < T < TSDW thus show a strong resemblance to the pseudogap phase of the cuprates where growing experimental evidences suggest a FS reconstruction due to certain density wave order. In this phase of the pnictides, the residual FS has a favorable topology for magnetically mediated pairing when the ordering moment of the SDW is small.", "publicationTitle": "arXiv:1208.3842", "publisher": "", "place": "", "date": "2012-08-19", "volume": "", "issue": "", "section": "", "partNumber": "", "partTitle": "", "pages": "", "series": "", "seriesTitle": "", "seriesText": "", "journalAbbreviation": "", "DOI": "", "citationKey": "", "url": "http://arxiv.org/abs/1208.3842", "accessDate": "2013-04-06T06:51:39Z", "PMID": "", "PMCID": "", "ISSN": "", "archive": "", "archiveLocation": "", "shortTitle": "", "language": "", "libraryCatalog": "arXiv.org", "callNumber": "", "rights": "", "extra": "", "tags": [ { "tag": "Condensed Matter - Materials Science", "type": 1 }, { "tag": "Condensed Matter - Strongly Correlated Electrons", "type": 1 }, { "tag": "Condensed Matter - Superconductivity", "type": 1 } ], "collections": [ "CAZG3C9W" ], "relations": {}, "dateAdded": "2013-04-06T06:51:39Z", "dateModified": "2013-04-06T06:51:39Z" } }, { "key": "TGHNTM6W", "version": 3, "library": { "type": "group", "id": 157928, "name": "Complex Oxides", "links": { "alternate": { "href": "https://www.zotero.org/groups/complex_oxides", "type": "text/html" } } }, "links": { "self": { "href": "https://api.zotero.org/groups/157928/items/TGHNTM6W", "type": "application/json" }, "alternate": { "href": "https://www.zotero.org/groups/complex_oxides/items/TGHNTM6W", "type": "text/html" }, "up": { "href": "https://api.zotero.org/groups/157928/items/68DQ4EAK", "type": "application/json" } }, "meta": { "createdByUser": { "id": 503034, "username": "tzhang18", "name": "", "links": { "alternate": { "href": "https://www.zotero.org/tzhang18", "type": "text/html" } } } }, "data": { "key": "TGHNTM6W", "version": 3, "parentItem": "68DQ4EAK", "itemType": "attachment", "linkMode": "linked_url", "title": "1208.3842 PDF", "accessDate": "2013-04-06T06:51:39Z", "url": "http://www.arxiv.org/pdf/1208.3842.pdf", "note": "", "contentType": "application/pdf", "charset": "", "tags": [], "relations": {}, "dateAdded": "2013-04-06T06:51:39Z", "dateModified": "2013-04-06T06:51:39Z" } }, { "key": "IU87AQEV", "version": 3, "library": { "type": "group", "id": 157928, "name": "Complex Oxides", "links": { "alternate": { "href": "https://www.zotero.org/groups/complex_oxides", "type": "text/html" } } }, "links": { "self": { "href": "https://api.zotero.org/groups/157928/items/IU87AQEV", "type": "application/json" }, "alternate": { "href": "https://www.zotero.org/groups/complex_oxides/items/IU87AQEV", "type": "text/html" }, "up": { "href": "https://api.zotero.org/groups/157928/items/68DQ4EAK", "type": "application/json" } }, "meta": { "createdByUser": { "id": 503034, "username": "tzhang18", "name": "", "links": { "alternate": { "href": "https://www.zotero.org/tzhang18", "type": "text/html" } } } }, "data": { "key": "IU87AQEV", "version": 3, "parentItem": "68DQ4EAK", "itemType": "attachment", "linkMode": "linked_url", "title": "arXiv.org Snapshot", "accessDate": "2013-04-06T06:51:39Z", "url": "http://arxiv.org/abs/1208.3842", "note": "", "contentType": "text/html", "charset": "", "tags": [], "relations": {}, "dateAdded": "2013-04-06T06:51:39Z", "dateModified": "2013-04-06T06:51:39Z" } }, { "key": "4R957VPJ", "version": 3, "library": { "type": "group", "id": 157928, "name": "Complex Oxides", "links": { "alternate": { "href": "https://www.zotero.org/groups/complex_oxides", "type": "text/html" } } }, "links": { "self": { "href": "https://api.zotero.org/groups/157928/items/4R957VPJ", "type": "application/json" }, "alternate": { "href": "https://www.zotero.org/groups/complex_oxides/items/4R957VPJ", "type": "text/html" }, "up": { "href": "https://api.zotero.org/groups/157928/items/S79P5BAI", "type": "application/json" } }, "meta": { "createdByUser": { "id": 503034, "username": "tzhang18", "name": "", "links": { "alternate": { "href": "https://www.zotero.org/tzhang18", "type": "text/html" } } } }, "data": { "key": "4R957VPJ", "version": 3, "parentItem": "S79P5BAI", "itemType": "attachment", "linkMode": "linked_url", "title": "Full Text PDF", "accessDate": "2013-04-06T06:50:13Z", "url": "http://www.nature.com/ncomms/journal/v4/n3/pdf/ncomms2592.pdf", "note": "", "contentType": "application/pdf", "charset": "", "tags": [], "relations": {}, "dateAdded": "2013-04-06T06:50:13Z", "dateModified": "2013-04-06T06:50:13Z" } }, { "key": "VSAAFA3R", "version": 3, "library": { "type": "group", "id": 157928, "name": "Complex Oxides", "links": { "alternate": { "href": "https://www.zotero.org/groups/complex_oxides", "type": "text/html" } } }, "links": { "self": { "href": "https://api.zotero.org/groups/157928/items/VSAAFA3R", "type": "application/json" }, "alternate": { "href": "https://www.zotero.org/groups/complex_oxides/items/VSAAFA3R", "type": "text/html" }, "up": { "href": "https://api.zotero.org/groups/157928/items/S79P5BAI", "type": "application/json" } }, "meta": { "createdByUser": { "id": 503034, "username": "tzhang18", "name": "", "links": { "alternate": { "href": "https://www.zotero.org/tzhang18", "type": "text/html" } } } }, "data": { "key": "VSAAFA3R", "version": 3, "parentItem": "S79P5BAI", "itemType": "attachment", "linkMode": "linked_url", "title": "Snapshot", "accessDate": "2013-04-06T06:50:13Z", "url": "http://www.nature.com/ncomms/journal/v4/n3/full/ncomms2592.html", "note": "", "contentType": "text/html", "charset": "", "tags": [], "relations": {}, "dateAdded": "2013-04-06T06:50:13Z", "dateModified": "2013-04-06T06:50:13Z" } }, { "key": "S79P5BAI", "version": 3, "library": { "type": "group", "id": 157928, "name": "Complex Oxides", "links": { "alternate": { "href": "https://www.zotero.org/groups/complex_oxides", "type": "text/html" } } }, "links": { "self": { "href": "https://api.zotero.org/groups/157928/items/S79P5BAI", "type": "application/json" }, "alternate": { "href": "https://www.zotero.org/groups/complex_oxides/items/S79P5BAI", "type": "text/html" } }, "meta": { "createdByUser": { "id": 503034, "username": "tzhang18", "name": "", "links": { "alternate": { "href": "https://www.zotero.org/tzhang18", "type": "text/html" } } }, "creatorSummary": "Cai et al.", "parsedDate": "2013", "numChildren": 2 }, "data": { "key": "S79P5BAI", "version": 3, "itemType": "journalArticle", "title": "Visualizing the microscopic coexistence of spin density wave and superconductivity in underdoped NaFe1−xCoxAs", "creators": [ { "creatorType": "author", "firstName": "Peng", "lastName": "Cai" }, { "creatorType": "author", "firstName": "Xiaodong", "lastName": "Zhou" }, { "creatorType": "author", "firstName": "Wei", "lastName": "Ruan" }, { "creatorType": "author", "firstName": "Aifeng", "lastName": "Wang" }, { "creatorType": "author", "firstName": "Xianhui", "lastName": "Chen" }, { "creatorType": "author", "firstName": "Dung-Hai", "lastName": "Lee" }, { "creatorType": "author", "firstName": "Yayu", "lastName": "Wang" } ], "abstractNote": "Although the origin of high temperature superconductivity in the iron pnictides is still under debate, it is widely believed that magnetic interactions or fluctuations have a crucial role in triggering Cooper pairing. A key issue regarding the iron pnictide phase diagram is whether long-range magnetic order can coexist with superconductivity microscopically. Here we use scanning tunnelling microscopy to investigate the local electronic structure of underdoped NaFe1−xCoxAs near the spin density wave and superconducting phase boundary. Spatially resolved spectroscopy directly reveals both the spin density wave and superconducting gaps at the same atomic location, providing compelling evidence for the microscopic coexistence of the two phases. The strengths of the two orders are shown to anti-correlate with each other, indicating the competition between them. This work implies that Cooper pairing in the iron pnictides can occur when portions of the Fermi surface are already gapped by the spin density wave order.", "publicationTitle": "Nature Communications", "publisher": "", "place": "", "date": "online 三月 12, 2013", "volume": "4", "issue": "", "section": "", "partNumber": "", "partTitle": "", "pages": "1596", "series": "", "seriesTitle": "", "seriesText": "", "journalAbbreviation": "Nat Commun", "DOI": "10.1038/ncomms2592", "citationKey": "", "url": "http://www.nature.com/ncomms/journal/v4/n3/full/ncomms2592.html", "accessDate": "2013-04-06T06:50:13Z", "PMID": "", "PMCID": "", "ISSN": "", "archive": "", "archiveLocation": "", "shortTitle": "", "language": "en", "libraryCatalog": "www.nature.com", "callNumber": "", "rights": "© 2013 Nature Publishing Group, a division of Macmillan Publishers Limited. All Rights Reserved.", "extra": "", "tags": [ { "tag": "Physical sciences", "type": 1 }, { "tag": "condensed matter", "type": 1 } ], "collections": [ "CAZG3C9W" ], "relations": {}, "dateAdded": "2013-04-06T06:50:13Z", "dateModified": "2013-04-06T06:50:13Z" } }, { "key": "8HEMEWBZ", "version": 3, "library": { "type": "group", "id": 157928, "name": "Complex Oxides", "links": { "alternate": { "href": "https://www.zotero.org/groups/complex_oxides", "type": "text/html" } } }, "links": { "self": { "href": "https://api.zotero.org/groups/157928/items/8HEMEWBZ", "type": "application/json" }, "alternate": { "href": "https://www.zotero.org/groups/complex_oxides/items/8HEMEWBZ", "type": "text/html" }, "up": { "href": "https://api.zotero.org/groups/157928/items/BAKPTPZC", "type": "application/json" } }, "meta": { "createdByUser": { "id": 503034, "username": "tzhang18", "name": "", "links": { "alternate": { "href": "https://www.zotero.org/tzhang18", "type": "text/html" } } } }, "data": { "key": "8HEMEWBZ", "version": 3, "parentItem": "BAKPTPZC", "itemType": "attachment", "linkMode": "linked_url", "title": "APS Full Text PDF", "accessDate": "2013-04-06T06:49:03Z", "url": "http://prx.aps.org/pdf/PRX/v2/i2/e021009", "note": "", "contentType": "application/pdf", "charset": "", "tags": [], "relations": {}, "dateAdded": "2013-04-06T06:49:03Z", "dateModified": "2013-04-06T06:49:03Z" } }, { "key": "BAKPTPZC", "version": 3, "library": { "type": "group", "id": 157928, "name": "Complex Oxides", "links": { "alternate": { "href": "https://www.zotero.org/groups/complex_oxides", "type": "text/html" } } }, "links": { "self": { "href": "https://api.zotero.org/groups/157928/items/BAKPTPZC", "type": "application/json" }, "alternate": { "href": "https://www.zotero.org/groups/complex_oxides/items/BAKPTPZC", "type": "text/html" } }, "meta": { "createdByUser": { "id": 503034, "username": "tzhang18", "name": "", "links": { "alternate": { "href": "https://www.zotero.org/tzhang18", "type": "text/html" } } }, "creatorSummary": "Hu and Hao", "parsedDate": "2012", "numChildren": 2 }, "data": { "key": "BAKPTPZC", "version": 3, "itemType": "journalArticle", "title": "S_{4} Symmetric Microscopic Model for Iron-Based Superconductors", "creators": [ { "creatorType": "author", "firstName": "Jiangping", "lastName": "Hu" }, { "creatorType": "author", "firstName": "Ningning", "lastName": "Hao" } ], "abstractNote": "Although iron-based superconductors are multiorbital systems with complicated band structures, we demonstrate that the low-energy physics which is responsible for their high-Tc superconductivity is essentially governed by an effective two-orbital Hamiltonian near half filling. This underlying electronic structure is protected by the S4 symmetry. With repulsive or strong next-nearest-neighbor antiferromagnetic exchange interactions, the model results in a robust A1g s-wave pairing which can be mapped exactly to the d-wave pairing observed in cuprates. The classification of the superconducting (SC) states according to the S4 symmetry leads to a natural prediction of the existence of two different phases, named the A and B phases. In the B phase, the superconducting order has an overall sign change along the c axis between the top and bottom As (or Se) planes in a single Fe-As (or Fe-Se) trilayer structure, the common building block of iron-based superconductors. The sign change is analogous to the sign change in the d-wave superconducting state of cuprates upon 90° rotation. Our derivation provides a unified understanding of iron pnictides and iron chalcogenides, and suggests that cuprates and iron-based superconductors share an identical high-Tc superconducting mechanism.", "publicationTitle": "Physical Review X", "publisher": "", "place": "", "date": "五月 30, 2012", "volume": "2", "issue": "2", "section": "", "partNumber": "", "partTitle": "", "pages": "021009", "series": "", "seriesTitle": "", "seriesText": "", "journalAbbreviation": "Phys. Rev. X", "DOI": "10.1103/PhysRevX.2.021009", "citationKey": "", "url": "http://link.aps.org/doi/10.1103/PhysRevX.2.021009", "accessDate": "2013-04-06T06:49:03Z", "PMID": "", "PMCID": "", "ISSN": "", "archive": "", "archiveLocation": "", "shortTitle": "", "language": "", "libraryCatalog": "APS", "callNumber": "", "rights": "", "extra": "", "tags": [], "collections": [ "7Q5HEHNA" ], "relations": {}, "dateAdded": "2013-04-06T06:49:03Z", "dateModified": "2013-04-06T06:49:03Z" } }, { "key": "QAKNDF66", "version": 3, "library": { "type": "group", "id": 157928, "name": "Complex Oxides", "links": { "alternate": { "href": "https://www.zotero.org/groups/complex_oxides", "type": "text/html" } } }, "links": { "self": { "href": "https://api.zotero.org/groups/157928/items/QAKNDF66", "type": "application/json" }, "alternate": { "href": "https://www.zotero.org/groups/complex_oxides/items/QAKNDF66", "type": "text/html" }, "up": { "href": "https://api.zotero.org/groups/157928/items/BAKPTPZC", "type": "application/json" } }, "meta": { "createdByUser": { "id": 503034, "username": "tzhang18", "name": "", "links": { "alternate": { "href": "https://www.zotero.org/tzhang18", "type": "text/html" } } } }, "data": { "key": "QAKNDF66", "version": 3, "parentItem": "BAKPTPZC", "itemType": "attachment", "linkMode": "linked_url", "title": "APS Snapshot", "accessDate": "2013-04-06T06:49:03Z", "url": "http://prx.aps.org/abstract/PRX/v2/i2/e021009", "note": "", "contentType": "text/html", "charset": "", "tags": [], "relations": {}, "dateAdded": "2013-04-06T06:49:03Z", "dateModified": "2013-04-06T06:49:03Z" } }, { "key": "XE49V7HR", "version": 3, "library": { "type": "group", "id": 157928, "name": "Complex Oxides", "links": { "alternate": { "href": "https://www.zotero.org/groups/complex_oxides", "type": "text/html" } } }, "links": { "self": { "href": "https://api.zotero.org/groups/157928/items/XE49V7HR", "type": "application/json" }, "alternate": { "href": "https://www.zotero.org/groups/complex_oxides/items/XE49V7HR", "type": "text/html" } }, "meta": { "createdByUser": { "id": 503034, "username": "tzhang18", "name": "", "links": { "alternate": { "href": "https://www.zotero.org/tzhang18", "type": "text/html" } } }, "creatorSummary": "Hu and Hao", "parsedDate": "2012-05-30", "numChildren": 0 }, "data": { "key": "XE49V7HR", "version": 3, "itemType": "journalArticle", "title": "S_{4} Symmetric Microscopic Model for Iron-Based Superconductors", "creators": [ { "creatorType": "author", "firstName": "Jiangping", "lastName": "Hu" }, { "creatorType": "author", "firstName": "Ningning", "lastName": "Hao" } ], "abstractNote": "Although iron-based superconductors are multiorbital systems with complicated band structures, we demonstrate that the low-energy physics which is responsible for their high-Tc superconductivity is essentially governed by an effective two-orbital Hamiltonian near half filling. This underlying electronic structure is protected by the S4 symmetry. With repulsive or strong next-nearest-neighbor antiferromagnetic exchange interactions, the model results in a robust A1g s-wave pairing which can be mapped exactly to the d-wave pairing observed in cuprates. The classification of the superconducting (SC) states according to the S4 symmetry leads to a natural prediction of the existence of two different phases, named the A and B phases. In the B phase, the superconducting order has an overall sign change along the c axis between the top and bottom As (or Se) planes in a single Fe-As (or Fe-Se) trilayer structure, the common building block of iron-based superconductors. The sign change is analogous to the sign change in the d-wave superconducting state of cuprates upon 90° rotation. Our derivation provides a unified understanding of iron pnictides and iron chalcogenides, and suggests that cuprates and iron-based superconductors share an identical high-Tc superconducting mechanism.", "publicationTitle": "Physical Review X", "publisher": "", "place": "", "date": "May 30, 2012", "volume": "2", "issue": "2", "section": "", "partNumber": "", "partTitle": "", "pages": "021009", "series": "", "seriesTitle": "", "seriesText": "", "journalAbbreviation": "Phys. Rev. X", "DOI": "10.1103/PhysRevX.2.021009", "citationKey": "", "url": "http://link.aps.org/doi/10.1103/PhysRevX.2.021009", "accessDate": "2012-06-14T18:22:42Z", "PMID": "", "PMCID": "", "ISSN": "", "archive": "", "archiveLocation": "", "shortTitle": "", "language": "", "libraryCatalog": "APS", "callNumber": "", "rights": "", "extra": "", "tags": [], "collections": [], "relations": {}, "dateAdded": "2013-04-06T06:45:00Z", "dateModified": "2013-04-06T06:45:00Z" } }, { "key": "HRDZNNAN", "version": 2, "library": { "type": "group", "id": 157928, "name": "Complex Oxides", "links": { "alternate": { "href": "https://www.zotero.org/groups/complex_oxides", "type": "text/html" } } }, "links": { "self": { "href": "https://api.zotero.org/groups/157928/items/HRDZNNAN", "type": "application/json" }, "alternate": { "href": "https://www.zotero.org/groups/complex_oxides/items/HRDZNNAN", "type": "text/html" } }, "meta": { "createdByUser": { "id": 503034, "username": "tzhang18", "name": "", "links": { "alternate": { "href": "https://www.zotero.org/tzhang18", "type": "text/html" } } }, "creatorSummary": "Kane and Mele", "parsedDate": "2005-09-28", "numChildren": 0 }, "data": { "key": "HRDZNNAN", "version": 2, "itemType": "journalArticle", "title": "Z_{2} Topological Order and the Quantum Spin Hall Effect", "creators": [ { "creatorType": "author", "firstName": "C. L.", "lastName": "Kane" }, { "creatorType": "author", "firstName": "E. J.", "lastName": "Mele" } ], "abstractNote": "The quantum spin Hall (QSH) phase is a time reversal invariant electronic state with a bulk electronic band gap that supports the transport of charge and spin in gapless edge states. We show that this phase is associated with a novel Z2 topological invariant, which distinguishes it from an ordinary insulator. The Z2 classification, which is defined for time reversal invariant Hamiltonians, is analogous to the Chern number classification of the quantum Hall effect. We establish the Z2 order of the QSH phase in the two band model of graphene and propose a generalization of the formalism applicable to multiband and interacting systems.", "publicationTitle": "Physical Review Letters", "publisher": "", "place": "", "date": "September 28, 2005", "volume": "95", "issue": "14", "section": "", "partNumber": "", "partTitle": "", "pages": "146802", "series": "", "seriesTitle": "", "seriesText": "", "journalAbbreviation": "Phys. Rev. Lett.", "DOI": "10.1103/PhysRevLett.95.146802", "citationKey": "", "url": "http://link.aps.org/doi/10.1103/PhysRevLett.95.146802", "accessDate": "2013-03-25T12:35:09Z", "PMID": "", "PMCID": "", "ISSN": "", "archive": "", "archiveLocation": "", "shortTitle": "", "language": "", "libraryCatalog": "APS", "callNumber": "", "rights": "", "extra": "", "tags": [], "collections": [ "7Q5HEHNA" ], "relations": {}, "dateAdded": "2013-04-06T06:45:00Z", "dateModified": "2013-04-06T06:45:00Z" } }, { "key": "5K5CJ37R", "version": 2, "library": { "type": "group", "id": 157928, "name": "Complex Oxides", "links": { "alternate": { "href": "https://www.zotero.org/groups/complex_oxides", "type": "text/html" } } }, "links": { "self": { "href": "https://api.zotero.org/groups/157928/items/5K5CJ37R", "type": "application/json" }, "alternate": { "href": "https://www.zotero.org/groups/complex_oxides/items/5K5CJ37R", "type": "text/html" } }, "meta": { "createdByUser": { "id": 503034, "username": "tzhang18", "name": "", "links": { "alternate": { "href": "https://www.zotero.org/tzhang18", "type": "text/html" } } }, "creatorSummary": "Li et al.", "parsedDate": "2012-10-16", "numChildren": 0 }, "data": { "key": "5K5CJ37R", "version": 2, "itemType": "journalArticle", "title": "Superconductivity in a single layer alkali-doped FeSe: a weakly coupled two-leg ladder system", "creators": [ { "creatorType": "author", "firstName": "Wei", "lastName": "Li" }, { "creatorType": "author", "firstName": "Hao", "lastName": "Ding" }, { "creatorType": "author", "firstName": "Pengfei", "lastName": "Zhang" }, { "creatorType": "author", "firstName": "Peng", "lastName": "Deng" }, { "creatorType": "author", "firstName": "Kai", "lastName": "Chang" }, { "creatorType": "author", "firstName": "Ke", "lastName": "He" }, { "creatorType": "author", "firstName": "Shuaihua", "lastName": "Ji" }, { "creatorType": "author", "firstName": "Lili", "lastName": "Wang" }, { "creatorType": "author", "firstName": "Xucun", "lastName": "Ma" }, { "creatorType": "author", "firstName": "Jian", "lastName": "Wu" }, { "creatorType": "author", "firstName": "Jiang-Ping", "lastName": "Hu" }, { "creatorType": "author", "firstName": "Qi-Kun", "lastName": "Xue" }, { "creatorType": "author", "firstName": "Xi", "lastName": "Chen" } ], "abstractNote": "We prepare single layer potassium-doped iron selenide (110) film by molecular beam expitaxy. Such a single layer film can be viewed as a two-dimensional system composed of weakly coupled two-leg iron ladders. Scanning tunneling spectroscopy reveals that superconductivity is developed in this two-leg ladder system. The superconducting gap is similar to that of the multi-layer films. However, the Fermi surface topology given by first-principles calculation is remarkably different from that of the bulk materials. Our results suggest that superconducting pairing is very short-ranged or takes place rather locally in iron-chalcogenides. The superconductivity is most likely driven by electron-electron correlation effect and is insensitive to the change of Fermi surfaces.", "publicationTitle": "arXiv:1210.4619", "publisher": "", "place": "", "date": "2012-10-16", "volume": "", "issue": "", "section": "", "partNumber": "", "partTitle": "", "pages": "", "series": "", "seriesTitle": "", "seriesText": "", "journalAbbreviation": "", "DOI": "", "citationKey": "", "url": "http://arxiv.org/abs/1210.4619", "accessDate": "2013-03-12T05:52:43Z", "PMID": "", "PMCID": "", "ISSN": "", "archive": "", "archiveLocation": "", "shortTitle": "Superconductivity in a single layer alkali-doped FeSe", "language": "", "libraryCatalog": "arXiv.org", "callNumber": "", "rights": "", "extra": "", "tags": [ { "tag": "Condensed Matter - Superconductivity", "type": 1 } ], "collections": [ "7Q5HEHNA" ], "relations": {}, "dateAdded": "2013-04-06T06:45:00Z", "dateModified": "2013-04-06T06:45:00Z" } }, { "key": "BE52WF7V", "version": 2, "library": { "type": "group", "id": 157928, "name": "Complex Oxides", "links": { "alternate": { "href": "https://www.zotero.org/groups/complex_oxides", "type": "text/html" } } }, "links": { "self": { "href": "https://api.zotero.org/groups/157928/items/BE52WF7V", "type": "application/json" }, "alternate": { "href": "https://www.zotero.org/groups/complex_oxides/items/BE52WF7V", "type": "text/html" } }, "meta": { "createdByUser": { "id": 503034, "username": "tzhang18", "name": "", "links": { "alternate": { "href": "https://www.zotero.org/tzhang18", "type": "text/html" } } }, "creatorSummary": "Bang et al.", "parsedDate": "2009", "numChildren": 0 }, "data": { "key": "BE52WF7V", "version": 2, "itemType": "journalArticle", "title": "Impurity effects on the ±s-wave state of the iron-based superconductors", "creators": [ { "creatorType": "author", "firstName": "Yunkyu", "lastName": "Bang" }, { "creatorType": "author", "firstName": "Han-Yong", "lastName": "Choi" }, { "creatorType": "author", "firstName": "Hyekyung", "lastName": "Won" } ], "abstractNote": "We studied the impurity scattering on the ±s-wave superconductor (SC), with realistic parameters for the Fe pnictide SCs. Using the T-matrix method, generalized for the two bands, we found that the strong scattering limit of impurities forms an off-centered resonance state inside the superconducting (SC) gap, which modifies, surprisingly, the density of states (DOS) of a fully opened gap to a V-shaped DOS as if in the case of a d-wave SC. This behavior provides coherent explanations to the several conflicting experiments of the Fe-based SC: (1) the V-shaped DOS observed in photoemission and tunneling spectroscopy but with an isotropic gap; (2) the power-law behavior of the nuclear-spin-lattice relaxation rate (1/T1∼Tα with α∼3) down to very low temperatures. We also extended the same T-matrix method to study the impurity suppression of the critical temperature Tc of the ±s-wave pairing state. We found that both magnetic and nonmagnetic impurities suppress Tc with a rate that is practically indistinguishable from the standard d-wave case despite a possibly large difference of the positive and the negative s-wave order parameter magnitudes.", "publicationTitle": "Physical Review B", "publisher": "", "place": "", "date": "二月 27, 2009", "volume": "79", "issue": "5", "section": "", "partNumber": "", "partTitle": "", "pages": "054529", "series": "", "seriesTitle": "", "seriesText": "", "journalAbbreviation": "Phys. Rev. B", "DOI": "10.1103/PhysRevB.79.054529", "citationKey": "", "url": "http://link.aps.org/doi/10.1103/PhysRevB.79.054529", "accessDate": "2012-07-29T02:57:49Z", "PMID": "", "PMCID": "", "ISSN": "", "archive": "", "archiveLocation": "", "shortTitle": "", "language": "", "libraryCatalog": "APS", "callNumber": "", "rights": "", "extra": "", "tags": [], "collections": [ "8FBMUI6V" ], "relations": {}, "dateAdded": "2013-04-06T06:45:00Z", "dateModified": "2013-04-06T06:45:00Z" } }, { "key": "CPAEED9V", "version": 2, "library": { "type": "group", "id": 157928, "name": "Complex Oxides", "links": { "alternate": { "href": "https://www.zotero.org/groups/complex_oxides", "type": "text/html" } } }, "links": { "self": { "href": "https://api.zotero.org/groups/157928/items/CPAEED9V", "type": "application/json" }, "alternate": { "href": "https://www.zotero.org/groups/complex_oxides/items/CPAEED9V", "type": "text/html" } }, "meta": { "createdByUser": { "id": 503034, "username": "tzhang18", "name": "", "links": { "alternate": { "href": "https://www.zotero.org/tzhang18", "type": "text/html" } } }, "creatorSummary": "Hu and Xu", "parsedDate": "2011-12-12", "numChildren": 0 }, "data": { "key": "CPAEED9V", "version": 2, "itemType": "journalArticle", "title": "Nematic orders in Iron-based superconductors", "creators": [ { "creatorType": "author", "firstName": "Jiangping", "lastName": "Hu" }, { "creatorType": "author", "firstName": "Cenke", "lastName": "Xu" } ], "abstractNote": "In the newly discovered iron-based superconductors, many experiments have demonstrated the existence of the rotational symmetry breaking nematic order, which has been a prevailing phenomenon in many correlated electronic systems. In this paper, we review nematic behaviors in iron-pnictides and the mechanism behind the development of the nematic order. We discuss evidences that support the spin-driven nematicity in iron-pnictides. Theories, results and predictions will be discussed based on this picture. We also briefly discuss the generalization of this theory to the nematicity in iron-chalcogenides.", "publicationTitle": "arXiv:1112.2713", "publisher": "", "place": "", "date": "2011-12-12", "volume": "", "issue": "", "section": "", "partNumber": "", "partTitle": "", "pages": "", "series": "", "seriesTitle": "", "seriesText": "", "journalAbbreviation": "", "DOI": "", "citationKey": "", "url": "http://arxiv.org/abs/1112.2713", "accessDate": "2012-07-26T18:55:06Z", "PMID": "", "PMCID": "", "ISSN": "", "archive": "", "archiveLocation": "", "shortTitle": "", "language": "", "libraryCatalog": "arXiv.org", "callNumber": "", "rights": "", "extra": "", "tags": [ { "tag": "Condensed Matter - Strongly Correlated Electrons", "type": 1 } ], "collections": [ "8FBMUI6V" ], "relations": {}, "dateAdded": "2013-04-06T06:45:00Z", "dateModified": "2013-04-06T06:45:00Z" } }, { "key": "Q6NDW558", "version": 2, "library": { "type": "group", "id": 157928, "name": "Complex Oxides", "links": { "alternate": { "href": "https://www.zotero.org/groups/complex_oxides", "type": "text/html" } } }, "links": { "self": { "href": "https://api.zotero.org/groups/157928/items/Q6NDW558", "type": "application/json" }, "alternate": { "href": "https://www.zotero.org/groups/complex_oxides/items/Q6NDW558", "type": "text/html" } }, "meta": { "createdByUser": { "id": 503034, "username": "tzhang18", "name": "", "links": { "alternate": { "href": "https://www.zotero.org/tzhang18", "type": "text/html" } } }, "creatorSummary": "Kuroki et al.", "parsedDate": "2008", "numChildren": 0 }, "data": { "key": "Q6NDW558", "version": 2, "itemType": "journalArticle", "title": "Unconventional Pairing Originating from the Disconnected Fermi Surfaces of Superconducting LaFeAsO_{1-x}F_{x}", "creators": [ { "creatorType": "author", "firstName": "Kazuhiko", "lastName": "Kuroki" }, { "creatorType": "author", "firstName": "Seiichiro", "lastName": "Onari" }, { "creatorType": "author", "firstName": "Ryotaro", "lastName": "Arita" }, { "creatorType": "author", "firstName": "Hidetomo", "lastName": "Usui" }, { "creatorType": "author", "firstName": "Yukio", "lastName": "Tanaka" }, { "creatorType": "author", "firstName": "Hiroshi", "lastName": "Kontani" }, { "creatorType": "author", "firstName": "Hideo", "lastName": "Aoki" } ], "abstractNote": "For a newly discovered iron-based high Tc superconductor LaFeAsO1-xFx, we have constructed a minimal model, where inclusion of all five Fe d bands is found to be necessary. The random-phase approximation is applied to the model to investigate the origin of superconductivity. We conclude that the multiple spin-fluctuation modes arising from the nesting across the disconnected Fermi surfaces realize an extended s-wave pairing, while d-wave pairing can also be another candidate.", "publicationTitle": "Physical Review Letters", "publisher": "", "place": "", "date": "2008", "volume": "101", "issue": "8", "section": "", "partNumber": "", "partTitle": "", "pages": "087004", "series": "", "seriesTitle": "", "seriesText": "", "journalAbbreviation": "Phys. Rev. Lett.", "DOI": "10.1103/PhysRevLett.101.087004", "citationKey": "", "url": "http://link.aps.org/doi/10.1103/PhysRevLett.101.087004", "accessDate": "2012-07-29T03:00:14Z", "PMID": "", "PMCID": "", "ISSN": "", "archive": "", "archiveLocation": "", "shortTitle": "", "language": "", "libraryCatalog": "APS", "callNumber": "", "rights": "", "extra": "", "tags": [], "collections": [ "8FBMUI6V" ], "relations": {}, "dateAdded": "2013-04-06T06:45:00Z", "dateModified": "2013-04-06T06:45:00Z" } }, { "key": "QDJQP949", "version": 2, "library": { "type": "group", "id": 157928, "name": "Complex Oxides", "links": { "alternate": { "href": "https://www.zotero.org/groups/complex_oxides", "type": "text/html" } } }, "links": { "self": { "href": "https://api.zotero.org/groups/157928/items/QDJQP949", "type": "application/json" }, "alternate": { "href": "https://www.zotero.org/groups/complex_oxides/items/QDJQP949", "type": "text/html" } }, "meta": { "createdByUser": { "id": 503034, "username": "tzhang18", "name": "", "links": { "alternate": { "href": "https://www.zotero.org/tzhang18", "type": "text/html" } } }, "creatorSummary": "He et al.", "parsedDate": "2012-07-29", "numChildren": 0 }, "data": { "key": "QDJQP949", "version": 2, "itemType": "journalArticle", "title": "Phase Diagram and High Temperature Superconductivity at 65 K in Tuning Carrier Concentration of Single-Layer FeSe Films", "creators": [ { "creatorType": "author", "firstName": "Shaolong", "lastName": "He" }, { "creatorType": "author", "firstName": "Junfeng", "lastName": "He" }, { "creatorType": "author", "firstName": "Wenhao", "lastName": "Zhang" }, { "creatorType": "author", "firstName": "Lin", "lastName": "Zhao" }, { "creatorType": "author", "firstName": "Defa", "lastName": "Liu" }, { "creatorType": "author", "firstName": "Xu", "lastName": "Liu" }, { "creatorType": "author", "firstName": "Daixiang", "lastName": "Mou" }, { "creatorType": "author", "firstName": "Yun-Bo", "lastName": "Ou" }, { "creatorType": "author", "firstName": "Qing-Yan", "lastName": "Wang" }, { "creatorType": "author", "firstName": "Zhi", "lastName": "Li" }, { "creatorType": "author", "firstName": "Lili", "lastName": "Wang" }, { "creatorType": "author", "firstName": "Yingying", "lastName": "Peng" }, { "creatorType": "author", "firstName": "Yan", "lastName": "Liu" }, { "creatorType": "author", "firstName": "Chaoyu", "lastName": "Chen" }, { "creatorType": "author", "firstName": "Li", "lastName": "Yu" }, { "creatorType": "author", "firstName": "Guodong", "lastName": "Liu" }, { "creatorType": "author", "firstName": "Xiaoli", "lastName": "Dong" }, { "creatorType": "author", "firstName": "Jun", "lastName": "Zhang" }, { "creatorType": "author", "firstName": "Chuangtian", "lastName": "Chen" }, { "creatorType": "author", "firstName": "Zuyan", "lastName": "Xu" }, { "creatorType": "author", "firstName": "Xi", "lastName": "Chen" }, { "creatorType": "author", "firstName": "Xucun", "lastName": "Ma" }, { "creatorType": "author", "firstName": "Qikun", "lastName": "Xue" }, { "creatorType": "author", "firstName": "X. J.", "lastName": "Zhou" } ], "abstractNote": "Superconductivity in the cuprate superconductors and the Fe-based superconductors is realized by doping the parent compound with charge carriers, or by application of high pressure, to suppress the antiferromagnetic state. Such a rich phase diagram is important in understanding superconductivity mechanism and other physics in the Cu- and Fe-based high temperature superconductors. In this paper, we report a phase diagram in the single-layer FeSe films grown on SrTiO3 substrate by an annealing procedure to tune the charge carrier concentration over a wide range. A dramatic change of the band structure and Fermi surface is observed, with two distinct phases identified that are competing during the annealing process. Superconductivity with a record high transition temperature (Tc) at ~65 K is realized by optimizing the annealing process. The wide tunability of the system across different phases, and its high-Tc, make the single-layer FeSe film ideal not only to investigate the superconductivity physics and mechanism, but also to study novel quantum phenomena and for potential applications.", "publicationTitle": "arXiv:1207.6823", "publisher": "", "place": "", "date": "2012-07-29", "volume": "", "issue": "", "section": "", "partNumber": "", "partTitle": "", "pages": "", "series": "", "seriesTitle": "", "seriesText": "", "journalAbbreviation": "", "DOI": "", "citationKey": "", "url": "http://arxiv.org/abs/1207.6823", "accessDate": "2012-08-14T18:20:06Z", "PMID": "", "PMCID": "", "ISSN": "", "archive": "", "archiveLocation": "", "shortTitle": "", "language": "", "libraryCatalog": "arXiv.org", "callNumber": "", "rights": "", "extra": "", "tags": [ { "tag": "Condensed Matter - Materials Science", "type": 1 }, { "tag": "Condensed Matter - Strongly Correlated Electrons", "type": 1 }, { "tag": "Condensed Matter - Superconductivity", "type": 1 } ], "collections": [ "R8JRC3SH" ], "relations": {}, "dateAdded": "2013-04-06T06:45:00Z", "dateModified": "2013-04-06T06:45:00Z" } }, { "key": "IRGVU3SA", "version": 2, "library": { "type": "group", "id": 157928, "name": "Complex Oxides", "links": { "alternate": { "href": "https://www.zotero.org/groups/complex_oxides", "type": "text/html" } } }, "links": { "self": { "href": "https://api.zotero.org/groups/157928/items/IRGVU3SA", "type": "application/json" }, "alternate": { "href": "https://www.zotero.org/groups/complex_oxides/items/IRGVU3SA", "type": "text/html" } }, "meta": { "createdByUser": { "id": 503034, "username": "tzhang18", "name": "", "links": { "alternate": { "href": "https://www.zotero.org/tzhang18", "type": "text/html" } } }, "creatorSummary": "Zhang et al.", "parsedDate": "2012", "numChildren": 0 }, "data": { "key": "IRGVU3SA", "version": 2, "itemType": "journalArticle", "title": "Nodal superconducting-gap structure in ferropnictide superconductor BaFe2(As0.7P0.3)2", "creators": [ { "creatorType": "author", "firstName": "Y.", "lastName": "Zhang" }, { "creatorType": "author", "firstName": "Z. R.", "lastName": "Ye" }, { "creatorType": "author", "firstName": "Q. Q.", "lastName": "Ge" }, { "creatorType": "author", "firstName": "F.", "lastName": "Chen" }, { "creatorType": "author", "firstName": "Juan", "lastName": "Jiang" }, { "creatorType": "author", "firstName": "M.", "lastName": "Xu" }, { "creatorType": "author", "firstName": "B. P.", "lastName": "Xie" }, { "creatorType": "author", "firstName": "D. L.", "lastName": "Feng" } ], "abstractNote": "The superconducting-gap distribution is a pivotal characteristic for a superconductor. Whereas the cuprates and conventional phonon-mediated superconductors are characterized by distinct d-wave and s-wave pairing symmetries with nodal and nodeless gap distributions respectively, the superconducting-gap distributions in iron-based superconductors are rather diversified. Whereas nodeless gap distributions have been directly observed in Ba1−xKxFe2As2, BaFe2−xCoxAs2, KxFe2−ySe2 and FeTe1−xSex (refs 1, 2, 3, 4), the signatures of nodal superconducting gaps have been reported in LaOFeP, LiFeP, KFe2As2, BaFe2(As1−xPx)2, BaFe2−xRuxAs2 and FeSe (refs 5, 6, 7, 8, 9, 10, 11, 12). We here report the angle-resolved photoemission spectroscopy measurements on the superconducting-gap structure of BaFe2(As0.7P0.3)2, and in particular the direct observation of a circular line node on the largest hole Fermi surface around the Z point at the Brillouin zone boundary. Our findings rule out a d-wave-pairing origin for the nodal gap, and establish the existence of nodes in iron pnictides under the s-wave pairing symmetry.", "publicationTitle": "Nature Physics", "publisher": "", "place": "", "date": "2012", "volume": "8", "issue": "5", "section": "", "partNumber": "", "partTitle": "", "pages": "371-375", "series": "", "seriesTitle": "", "seriesText": "", "journalAbbreviation": "", "DOI": "10.1038/nphys2248", "citationKey": "", "url": "http://www.nature.com/nphys/journal/v8/n5/abs/nphys2248.html", "accessDate": "2012-07-25T20:15:51Z", "PMID": "", "PMCID": "", "ISSN": "1745-2473", "archive": "", "archiveLocation": "", "shortTitle": "", "language": "en", "libraryCatalog": "www.nature.com", "callNumber": "", "rights": "© 2012 Nature Publishing Group", "extra": "", "tags": [ { "tag": "Condensed-matter physics", "type": 1 } ], "collections": [ "R8JRC3SH" ], "relations": {}, "dateAdded": "2013-04-06T06:45:00Z", "dateModified": "2013-04-06T06:45:00Z" } }, { "key": "FRM4ST2H", "version": 2, "library": { "type": "group", "id": 157928, "name": "Complex Oxides", "links": { "alternate": { "href": "https://www.zotero.org/groups/complex_oxides", "type": "text/html" } } }, "links": { "self": { "href": "https://api.zotero.org/groups/157928/items/FRM4ST2H", "type": "application/json" }, "alternate": { "href": "https://www.zotero.org/groups/complex_oxides/items/FRM4ST2H", "type": "text/html" } }, "meta": { "createdByUser": { "id": 503034, "username": "tzhang18", "name": "", "links": { "alternate": { "href": "https://www.zotero.org/tzhang18", "type": "text/html" } } }, "creatorSummary": "Zhang et al.", "parsedDate": "2011", "numChildren": 0 }, "data": { "key": "FRM4ST2H", "version": 2, "itemType": "journalArticle", "title": "Nodeless superconducting gap in AxFe2Se2 (A=K,Cs) revealed by angle-resolved photoemission spectroscopy", "creators": [ { "creatorType": "author", "firstName": "Y.", "lastName": "Zhang" }, { "creatorType": "author", "firstName": "L. X.", "lastName": "Yang" }, { "creatorType": "author", "firstName": "M.", "lastName": "Xu" }, { "creatorType": "author", "firstName": "Z. R.", "lastName": "Ye" }, { "creatorType": "author", "firstName": "F.", "lastName": "Chen" }, { "creatorType": "author", "firstName": "C.", "lastName": "He" }, { "creatorType": "author", "firstName": "H. C.", "lastName": "Xu" }, { "creatorType": "author", "firstName": "J.", "lastName": "Jiang" }, { "creatorType": "author", "firstName": "B. P.", "lastName": "Xie" }, { "creatorType": "author", "firstName": "J. J.", "lastName": "Ying" }, { "creatorType": "author", "firstName": "X. F.", "lastName": "Wang" }, { "creatorType": "author", "firstName": "X. H.", "lastName": "Chen" }, { "creatorType": "author", "firstName": "J. P.", "lastName": "Hu" }, { "creatorType": "author", "firstName": "M.", "lastName": "Matsunami" }, { "creatorType": "author", "firstName": "S.", "lastName": "Kimura" }, { "creatorType": "author", "firstName": "D. L.", "lastName": "Feng" } ], "abstractNote": "Pairing symmetry is a fundamental property that characterizes a superconductor. For the iron-based high-temperature superconductors, an s±-wave pairing symmetry has received increasing experimental and theoretical support. More specifically, the superconducting order parameter is an isotropic s-wave type around a particular Fermi surface, but it has opposite signs between the hole Fermi surfaces at the zone centre and the electron Fermi surfaces at the zone corners. Here we report the low-energy electronic structure of the newly discovered superconductors, AxFe2Se2 (A=K,Cs) with a superconducting transition temperature (Tc) of about 30 K. We found AxFe2Se2 (A=K,Cs) is the most heavily electron-doped among all iron-based superconductors. Large electron Fermi surfaces are observed around the zone corners, with an almost isotropic superconducting gap of ~10.3 meV, whereas there is no hole Fermi surface near the zone centre, which demonstrates that interband scattering or Fermi surface nesting is not a necessary ingredient for the unconventional superconductivity in iron-based superconductors. Thus, the sign change in the s± pairing symmetry driven by the interband scattering as suggested in many weak coupling theories becomes conceptually irrelevant in describing the superconducting state here. A more conventional s-wave pairing is probably a better description.", "publicationTitle": "Nature Materials", "publisher": "", "place": "", "date": "2011", "volume": "10", "issue": "4", "section": "", "partNumber": "", "partTitle": "", "pages": "273-277", "series": "", "seriesTitle": "", "seriesText": "", "journalAbbreviation": "", "DOI": "10.1038/nmat2981", "citationKey": "", "url": "http://www.nature.com/nmat/journal/v10/n4/full/nmat2981.html", "accessDate": "2012-07-25T20:15:18Z", "PMID": "", "PMCID": "", "ISSN": "1476-1122", "archive": "", "archiveLocation": "", "shortTitle": "", "language": "en", "libraryCatalog": "www.nature.com", "callNumber": "", "rights": "© 2011 Nature Publishing Group", "extra": "", "tags": [ { "tag": "Electronic materials", "type": 1 }, { "tag": "Superconductors", "type": 1 } ], "collections": [ "R8JRC3SH" ], "relations": {}, "dateAdded": "2013-04-06T06:45:00Z", "dateModified": "2013-04-06T06:45:00Z" } }, { "key": "D6PIT36E", "version": 2, "library": { "type": "group", "id": 157928, "name": "Complex Oxides", "links": { "alternate": { "href": "https://www.zotero.org/groups/complex_oxides", "type": "text/html" } } }, "links": { "self": { "href": "https://api.zotero.org/groups/157928/items/D6PIT36E", "type": "application/json" }, "alternate": { "href": "https://www.zotero.org/groups/complex_oxides/items/D6PIT36E", "type": "text/html" } }, "meta": { "createdByUser": { "id": 503034, "username": "tzhang18", "name": "", "links": { "alternate": { "href": "https://www.zotero.org/tzhang18", "type": "text/html" } } }, "creatorSummary": "Liu et al.", "parsedDate": "2012-07-03", "numChildren": 0 }, "data": { "key": "D6PIT36E", "version": 2, "itemType": "journalArticle", "title": "Electronic origin of high-temperature superconductivity in single-layer FeSe superconductor", "creators": [ { "creatorType": "author", "firstName": "Defa", "lastName": "Liu" }, { "creatorType": "author", "firstName": "Wenhao", "lastName": "Zhang" }, { "creatorType": "author", "firstName": "Daixiang", "lastName": "Mou" }, { "creatorType": "author", "firstName": "Junfeng", "lastName": "He" }, { "creatorType": "author", "firstName": "Yun-Bo", "lastName": "Ou" }, { "creatorType": "author", "firstName": "Qing-Yan", "lastName": "Wang" }, { "creatorType": "author", "firstName": "Zhi", "lastName": "Li" }, { "creatorType": "author", "firstName": "Lili", "lastName": "Wang" }, { "creatorType": "author", "firstName": "Lin", "lastName": "Zhao" }, { "creatorType": "author", "firstName": "Shaolong", "lastName": "He" }, { "creatorType": "author", "firstName": "Yingying", "lastName": "Peng" }, { "creatorType": "author", "firstName": "Xu", "lastName": "Liu" }, { "creatorType": "author", "firstName": "Chaoyu", "lastName": "Chen" }, { "creatorType": "author", "firstName": "Li", "lastName": "Yu" }, { "creatorType": "author", "firstName": "Guodong", "lastName": "Liu" }, { "creatorType": "author", "firstName": "Xiaoli", "lastName": "Dong" }, { "creatorType": "author", "firstName": "Jun", "lastName": "Zhang" }, { "creatorType": "author", "firstName": "Chuangtian", "lastName": "Chen" }, { "creatorType": "author", "firstName": "Zuyan", "lastName": "Xu" }, { "creatorType": "author", "firstName": "Jiangping", "lastName": "Hu" }, { "creatorType": "author", "firstName": "Xi", "lastName": "Chen" }, { "creatorType": "author", "firstName": "Xucun", "lastName": "Ma" }, { "creatorType": "author", "firstName": "Qikun", "lastName": "Xue" }, { "creatorType": "author", "firstName": "X. J.", "lastName": "Zhou" } ], "abstractNote": "The recent discovery of high-temperature superconductivity in iron-based compounds has attracted much attention. How to further increase the superconducting transition temperature (Tc) and how to understand the superconductivity mechanism are two prominent issues facing the current study of iron-based superconductors. The latest report of high-Tc superconductivity in a single-layer FeSe is therefore both surprising and significant. Here we present investigations of the electronic structure and superconducting gap of the single-layer FeSe superconductor. Its Fermi surface is distinct from other iron-based superconductors, consisting only of electron-like pockets near the zone corner without indication of any Fermi surface around the zone centre. Nearly isotropic superconducting gap is observed in this strictly two-dimensional system. The temperature dependence of the superconducting gap gives a transition temperature Tc~ 55 K. These results have established a clear case that such a simple electronic structure is compatible with high-Tc superconductivity in iron-based superconductors.", "publicationTitle": "Nature Communications", "publisher": "", "place": "", "date": "2012-07-03", "volume": "3", "issue": "", "section": "", "partNumber": "", "partTitle": "", "pages": "931", "series": "", "seriesTitle": "", "seriesText": "", "journalAbbreviation": "", "DOI": "10.1038/ncomms1946", "citationKey": "", "url": "http://www.nature.com/ncomms/journal/v3/n7/full/ncomms1946.html", "accessDate": "2012-07-26T14:58:15Z", "PMID": "", "PMCID": "", "ISSN": "2041-1723", "archive": "", "archiveLocation": "", "shortTitle": "", "language": "en", "libraryCatalog": "www.nature.com", "callNumber": "", "rights": "© 2012 Nature Publishing Group, a division of Macmillan Publishers Limited. All Rights Reserved.", "extra": "", "tags": [ { "tag": "Physical sciences", "type": 1 }, { "tag": "condensed matter", "type": 1 }, { "tag": "materials science", "type": 1 } ], "collections": [ "R8JRC3SH" ], "relations": {}, "dateAdded": "2013-04-06T06:45:00Z", "dateModified": "2013-04-06T06:45:00Z" } }, { "key": "M4PKRTCJ", "version": 2, "library": { "type": "group", "id": 157928, "name": "Complex Oxides", "links": { "alternate": { "href": "https://www.zotero.org/groups/complex_oxides", "type": "text/html" } } }, "links": { "self": { "href": "https://api.zotero.org/groups/157928/items/M4PKRTCJ", "type": "application/json" }, "alternate": { "href": "https://www.zotero.org/groups/complex_oxides/items/M4PKRTCJ", "type": "text/html" } }, "meta": { "createdByUser": { "id": 503034, "username": "tzhang18", "name": "", "links": { "alternate": { "href": "https://www.zotero.org/tzhang18", "type": "text/html" } } }, "creatorSummary": "Li et al.", "parsedDate": "2012-07-31", "numChildren": 0 }, "data": { "key": "M4PKRTCJ", "version": 2, "itemType": "journalArticle", "title": "KFe_{2}Se_{2} is the Parent Compound of K-Doped Iron Selenide Superconductors", "creators": [ { "creatorType": "author", "firstName": "Wei", "lastName": "Li" }, { "creatorType": "author", "firstName": "Hao", "lastName": "Ding" }, { "creatorType": "author", "firstName": "Zhi", "lastName": "Li" }, { "creatorType": "author", "firstName": "Peng", "lastName": "Deng" }, { "creatorType": "author", "firstName": "Kai", "lastName": "Chang" }, { "creatorType": "author", "firstName": "Ke", "lastName": "He" }, { "creatorType": "author", "firstName": "Shuaihua", "lastName": "Ji" }, { "creatorType": "author", "firstName": "Lili", "lastName": "Wang" }, { "creatorType": "author", "firstName": "Xucun", "lastName": "Ma" }, { "creatorType": "author", "firstName": "Jiang-Ping", "lastName": "Hu" }, { "creatorType": "author", "firstName": "Xi", "lastName": "Chen" }, { "creatorType": "author", "firstName": "Qi-Kun", "lastName": "Xue" } ], "abstractNote": "We elucidate the existing controversies in the newly discovered K-doped iron selenide (KxFe2-ySe2-z) superconductors. The stoichiometric KFe2Se2 with √2×√2 charge ordering was identified as the parent compound of KxFe2-ySe2-z superconductor using scanning tunneling microscopy and spectroscopy. The superconductivity is induced in KFe2Se2 by either Se vacancies or interacting with the antiferromagnetic K2Fe4Se5 compound. In total, four phases were found to exist in KxFe2-ySe2-z: parent compound KFe2Se2, superconducting KFe2Se2 with √2×√5 charge ordering, superconducting KFe2Se2-z with Se vacancies, and insulating K2Fe4Se5 with √5×√5 Fe vacancy order. The phase separation takes place at the mesoscopic scale under standard molecular beam epitaxy conditions.", "publicationTitle": "Physical Review Letters", "publisher": "", "place": "", "date": "July 31, 2012", "volume": "109", "issue": "5", "section": "", "partNumber": "", "partTitle": "", "pages": "057003", "series": "", "seriesTitle": "", "seriesText": "", "journalAbbreviation": "Phys. Rev. Lett.", "DOI": "10.1103/PhysRevLett.109.057003", "citationKey": "", "url": "http://link.aps.org/doi/10.1103/PhysRevLett.109.057003", "accessDate": "2012-08-03T22:25:21Z", "PMID": "", "PMCID": "", "ISSN": "", "archive": "", "archiveLocation": "", "shortTitle": "", "language": "", "libraryCatalog": "APS", "callNumber": "", "rights": "", "extra": "", "tags": [], "collections": [ "CAZG3C9W" ], "relations": {}, "dateAdded": "2013-04-06T06:45:00Z", "dateModified": "2013-04-06T06:45:00Z" } }, { "key": "DZ4UR4EG", "version": 2, "library": { "type": "group", "id": 157928, "name": "Complex Oxides", "links": { "alternate": { "href": "https://www.zotero.org/groups/complex_oxides", "type": "text/html" } } }, "links": { "self": { "href": "https://api.zotero.org/groups/157928/items/DZ4UR4EG", "type": "application/json" }, "alternate": { "href": "https://www.zotero.org/groups/complex_oxides/items/DZ4UR4EG", "type": "text/html" } }, "meta": { "createdByUser": { "id": 503034, "username": "tzhang18", "name": "", "links": { "alternate": { "href": "https://www.zotero.org/tzhang18", "type": "text/html" } } }, "creatorSummary": "Hanaguri et al.", "parsedDate": "2012-06-07", "numChildren": 0 }, "data": { "key": "DZ4UR4EG", "version": 2, "itemType": "journalArticle", "title": "Scanning tunneling microscopy/spectroscopy of vortices in LiFeAs", "creators": [ { "creatorType": "author", "firstName": "T.", "lastName": "Hanaguri" }, { "creatorType": "author", "firstName": "K.", "lastName": "Kitagawa" }, { "creatorType": "author", "firstName": "K.", "lastName": "Matsubayashi" }, { "creatorType": "author", "firstName": "Y.", "lastName": "Mazaki" }, { "creatorType": "author", "firstName": "Y.", "lastName": "Uwatoko" }, { "creatorType": "author", "firstName": "H.", "lastName": "Takagi" } ], "abstractNote": "We investigate vortices in LiFeAs using scanning tunneling microscopy/spectroscopy. Zero-field tunneling spectra show two superconducting gaps without detectable spectral weight near the Fermi energy, evidencing fully gapped multiband superconductivity. We image vortices in a wide field range from 0.1 T to 11 T by mapping the tunneling conductance at the Fermi energy. A quasihexagonal vortex lattice at low field contains domain boundaries which consist of alternating vortices with unusual coordination numbers of 5 and 7. With increasing field, the domain boundaries become ill defined, resulting in a uniformly disordered vortex matter. Tunneling spectra taken at the vortex center are characterized by a sharp peak just below the Fermi energy, apparently violating particle-hole symmetry. The image of each vortex shows energy-dependent 4-fold anisotropy which may be associated with the anisotropy of the Fermi surface. The vortex radius shrinks with decreasing temperature and becomes smaller than the coherence length estimated from the upper critical field. This is direct evidence of the Kramer-Pesch effect expected in a clean superconductor.", "publicationTitle": "Physical Review B", "publisher": "", "place": "", "date": "June 07, 2012", "volume": "85", "issue": "21", "section": "", "partNumber": "", "partTitle": "", "pages": "214505", "series": "", "seriesTitle": "", "seriesText": "", "journalAbbreviation": "Phys. Rev. B", "DOI": "10.1103/PhysRevB.85.214505", "citationKey": "", "url": "http://link.aps.org/doi/10.1103/PhysRevB.85.214505", "accessDate": "2012-07-25T20:11:52Z", "PMID": "", "PMCID": "", "ISSN": "", "archive": "", "archiveLocation": "", "shortTitle": "", "language": "", "libraryCatalog": "APS", "callNumber": "", "rights": "", "extra": "", "tags": [], "collections": [ "CAZG3C9W" ], "relations": {}, "dateAdded": "2013-04-06T06:45:00Z", "dateModified": "2013-04-06T06:45:00Z" } }, { "key": "D3UT7TG6", "version": 2, "library": { "type": "group", "id": 157928, "name": "Complex Oxides", "links": { "alternate": { "href": "https://www.zotero.org/groups/complex_oxides", "type": "text/html" } } }, "links": { "self": { "href": "https://api.zotero.org/groups/157928/items/D3UT7TG6", "type": "application/json" }, "alternate": { "href": "https://www.zotero.org/groups/complex_oxides/items/D3UT7TG6", "type": "text/html" } }, "meta": { "createdByUser": { "id": 503034, "username": "tzhang18", "name": "", "links": { "alternate": { "href": "https://www.zotero.org/tzhang18", "type": "text/html" } } }, "creatorSummary": "Zhou et al.", "parsedDate": "2012-07-17", "numChildren": 0 }, "data": { "key": "D3UT7TG6", "version": 2, "itemType": "journalArticle", "title": "Evolution from Unconventional Spin Density Wave to Superconductivity and a Pseudogaplike Phase in NaFe_{1-x}Co_{x}As", "creators": [ { "creatorType": "author", "firstName": "Xiaodong", "lastName": "Zhou" }, { "creatorType": "author", "firstName": "Peng", "lastName": "Cai" }, { "creatorType": "author", "firstName": "Aifeng", "lastName": "Wang" }, { "creatorType": "author", "firstName": "Wei", "lastName": "Ruan" }, { "creatorType": "author", "firstName": "Cun", "lastName": "Ye" }, { "creatorType": "author", "firstName": "Xianhui", "lastName": "Chen" }, { "creatorType": "author", "firstName": "Yizhuang", "lastName": "You" }, { "creatorType": "author", "firstName": "Zheng-Yu", "lastName": "Weng" }, { "creatorType": "author", "firstName": "Yayu", "lastName": "Wang" } ], "abstractNote": "We report the doping, temperature, and spatial evolutions of the electronic structure of NaFe1-xCoxAs studied by scanning tunneling microscopy. In the parent state we directly observe the spin density wave gap, which exhibits unconventional features that are incompatible with simple Fermi surface nesting. The optimally doped sample has a single superconducting gap, but in the overdoped regime a novel pseudogaplike feature emerges. The pseudogaplike phase coexists with superconductivity in the ground state, persists well into the normal state, and shows strong spatial variations. The characteristics of the three distinct electronic states revealed here shed important new lights on the microscopic models for the iron-based superconductors.", "publicationTitle": "Physical Review Letters", "publisher": "", "place": "", "date": "July 17, 2012", "volume": "109", "issue": "3", "section": "", "partNumber": "", "partTitle": "", "pages": "037002", "series": "", "seriesTitle": "", "seriesText": "", "journalAbbreviation": "Phys. Rev. Lett.", "DOI": "10.1103/PhysRevLett.109.037002", "citationKey": "", "url": "http://link.aps.org/doi/10.1103/PhysRevLett.109.037002", "accessDate": "2012-07-25T20:03:06Z", "PMID": "", "PMCID": "", "ISSN": "", "archive": "", "archiveLocation": "", "shortTitle": "", "language": "", "libraryCatalog": "APS", "callNumber": "", "rights": "", "extra": "", "tags": [], "collections": [ "CAZG3C9W" ], "relations": {}, "dateAdded": "2013-04-06T06:45:00Z", "dateModified": "2013-04-06T06:45:00Z" } } ]