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Anisotropic upper critical field and possible Fulde-Ferrel-Larkin-Ovchinnikov state in the stoichiometric pnictide superconductor LiFeAs

TitleAnisotropic upper critical field and possible Fulde-Ferrel-Larkin-Ovchinnikov state in the stoichiometric pnictide superconductor LiFeAs
Publication TypeJournal Article
Year of Publication2011
AuthorsCho K, Kim H, Tanatar MA, Song YJ, Kwon YS, Coniglio WA, Agosta CC, Gurevich A, Prozorov R
Journal TitlePhysical Review B
Volume83
Pages060502
Date Published02
Type of ArticleArticle
ISBN Number1098-0121
Accession NumberISI:000287031000002
Keywordsheat, MAGNETIC-FIELDS, parallel, sr2ruo4, UNCONVENTIONAL SUPERCONDUCTORS, upt3
Abstract

Measurements of the temperature and angular dependencies of the upper critical field H-c2 of a stoichiometric single crystal LiFeAs in pulsed magnetic fields up to 50 T were performed using a tunnel diode resonator. Complete H-c2(parallel to c)(T) and H-c2(perpendicular to c)(T) functions with H-c2(parallel to c)(0) = 17 +/- 1 T, H-c2(perpendicular to c) (0) = 26 +/- 1 T, and the anisotropy parameter gamma(H)(T) equivalent to H-c2(perpendicular to c) / H-c2(parallel to c) decreasing from 2.5 at T-c to 1.5 at T << T-c were obtained. The results for both orientations are in excellent agreement with a theory of H-c2 for two-band s(+/-) pairing in the clean limit. We show that H-c2(parallel to c)(T) is mostly limited by the orbital pair breaking, whereas the shape of H-c2(perpendicular to c)(T) indicates strong paramagnetic Pauli limiting and the inhomogeneous Fulde-Ferrel-Larkin-Ovchinnikov state below T-F similar to 5 K.
URL<Go to ISI>://000287031000002
DOI10.1103/PhysRevB.83.060502
Alternate JournalPhys. Rev. B