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Upper critical field of KFe2As2 under pressure: A test for the change in the superconducting gap structure

TitleUpper critical field of KFe2As2 under pressure: A test for the change in the superconducting gap structure
Publication TypeJournal Article
Year of Publication2014
AuthorsTaufour, V, Foroozani, N, Tanatar, MA, Lim, J, Kaluarachchi, U, Kim, SK, Liu, Y, Lograsso, TA, Kogan, VG, Prozorov, R, Bud'ko, SL, Schilling, JS, Canfield, PC
JournalPhysical Review B
Volume89
Pagination220509
Date Published06
Type of ArticleArticle
ISBN Number1098-0121
Accession NumberWOS:000338652100002
Keywordsdependence, gpa, hydrostatic limits, kbar, line, liquids, temperature
Abstract

We report measurements of electrical resistivity under pressure to 5.8 GPa, magnetization to 6.7 GPa, and ac susceptibility to 7.1 GPa in KFe2As2. The previously reported change of slope in the pressure dependence of the superconducting transition temperature Tc (p) at a pressure p*1.8 GPa is confirmed, and Tc (p) is found to be nearly constant above p* up to 7.1 GPa. The T - p phase diagram is very sensitive to the pressure conditions as a consequence of the anisotropic uniaxial pressure dependence of Tc. Across p*, a change in the behavior of the upper critical field is revealed through a scaling analysis of the slope of Hc2 with the effective mass as determined from the A coefficient of the T 2 term of the temperature-dependent resistivity. We show that this scaling provides a quantitative test for the changes of the superconducting gap structure and suggests the development of a kz modulation of the superconducting gap above p* as a most likely explanation.

DOI10.1103/PhysRevB.89.220509
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