Campus Units

Physics and Astronomy, Ames Laboratory

Document Type

Article

Publication Version

Published Version

Publication Date

4-1-2020

Journal or Book Title

Physical Review B

Volume

101

Issue

13

First Page

134502

DOI

10.1103/PhysRevB.101.134502

Abstract

The upper critical field of multiband superconductors is an important quantity that can reveal details about the nature of the superconducting pairing. Here we experimentally map out the complete upper-critical-field phase diagram of a stoichiometric superconductor, CaKFe4As4, up to 90T for different orientations of the magnetic field and at temperatures down to 4.2K. The upper critical fields are extremely large, reaching values close to ∼3Tc at the lowest temperature, and the anisotropy decreases dramatically with temperature, leading to essentially isotropic superconductivity at 4.2K. We find that the temperature dependence of the upper critical field can be well described by a two-band model in the clean limit with band-coupling parameters favoring intraband over interband interactions. The large Pauli paramagnetic effects together with the presence of the shallow bands is consistent with the stabilization of an FFLO state at low temperatures in this clean superconductor.

Comments

This article is published as Bristow, Matthew, William Knafo, Pascal Reiss, William Meier, Paul C. Canfield, Stephen J. Blundell, and Amalia I. Coldea. "Competing pairing interactions responsible for the large upper critical field in a stoichiometric iron-based superconductor CaKFe 4 As 4." Physical Review B 101, no. 13 (2020): 134502. DOI: 10.1103/PhysRevB.101.134502. Posted with permission.

Copyright Owner

American Physical Society

Language

en

File Format

application/pdf

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