Publication Date

6-4-2020

Department

Ames Laboratory; Physics and Astronomy

Campus Units

Physics and Astronomy, Ames Laboratory

OSTI ID+

1633643

Report Number

IS-J 10247

DOI

10.1103/PhysRevB.101.214503

Journal Title

Physical Review B

Volume Number

101

Issue Number

21

First Page

214503

Abstract

High-precision radio-frequency magnetic susceptibility measurements were performed on single crystals of fully deuterated kappa-(ET)(2)Cu[N(CN)(2)]Br, hereafter designated as kappa-(D8 ET)(2)Cu[N(CN)(2)]Br. This material phase separates into superconducting and antiferromagnetic regions, the degree of which depends strongly upon the cooling rate. We show that the screening fraction rise varies logarithmically with the cooling rate over nearly five decades. The average size of superconducting regions is estimated to vary from 5 to 40 mu m, depending upon cooling rate, consistent with previous infrared microscopy measurements. In the region T less than or similar to T-c/3, the effective magnetic penetration depth exhibits power-law behavior lambda(T) - lambda(0) similar to T-n with n = 1.6, independent of the cooling rate. Changes in cooling rate and the consequent phase separation evidently do not introduce the kind of disorder that would alter the exponent n in a d-wave superconductor. The exponent remains close to n = 1.5, reported in single crystals of kappa-(ET)(2)Cu[N(CN)(2)]Br and kappa-(ET)(2)Cu(NCS)(2) [A. Carrington et al., Phys. Rev. Lett 83. 4172 (1999)]. The transition temperature fell linearly with 1 - eta(sc). Measurements were also made on kappa-(ET)(2)Cu[N(CN)(2)]Cl of normal isotopic abundance in which a very small amount of superconducting phase rise eta(sc) approximate to 10(-4) developed, presumably through the strain-induced sample mounting. This material showed a power-law exponent of n = 1.64, independent of the cooling rate.

DOE Contract Number(s)

AC02-07CH11358; DMR-10-05708

Language

en

Publisher

Iowa State University Digital Repository, Ames IA (United States)

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