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arXiv · 2109.13712

Supercurrents and spontaneous time-reversal symmetry breaking by nonmagnetic disorder in unconventional superconductors

Clara N. Breiø·P. J. Hirschfeld·Brian M. Andersen
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Abstract

Recently, a theoretical study [Li {\it et al.},~npj Quantum Materials 6, 36 (2021)] investigated a model of a disordered $d$-wave superconductor, and reported local time-reversal symmetry breaking current loops for sufficiently high disorder levels. Since the pure $d$-wave superconducting state does not break time-reversal symmetry, it is surprising that such persistent currents arise purely from nonmagnetic disorder. Here we perform a detailed theoretical investigation of such disorder-induced orbital currents, and show that the occurrence of the currents can be traced to local extended $s$-wave pairing. We discuss the energetics leading to regions of $s\pm id$ order, which support spontaneous local currents in the presence of inhomogeneous density modulations.

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Clara N. Breiø, P. J. Hirschfeld, Brian M. Andersen. 2021-09-28. Supercurrents and spontaneous time-reversal symmetry breaking by nonmagnetic disorder in unconventional superconductors. https://doi.org/10.1103/physrevb.105.014504

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