Spontaneous time-reversal symmetry breaking by disorder in superconductors

• DOI: 10.3389/fphy.2024.1353425
• Publication Date: 2024-05-20T08:19:59Z
• Authors: Brian M. Andersen; Andreas Kreisel; P. J. Hirschfeld
• Keywords: T-symmetry

A growing number of superconducting materials display evidence for spontaneous time-reversal symmetry breaking (TRSB) below their critical transition temperatures. Precisely what this implies the nature ground state such materials, however, is often not straightforward to infer. We review experimental status and survey different theoretical mechanisms generation TRSB in superconductors. In cases where a complex combination two order parameter components realized, defects, dislocations sample edges may generate superflow patterns that can be picked up by magnetic probes. However, even single-component condensates do break pure bulk phases also support signatures magnetism inside state. This includes, example, localized orbital current or spin-polarization near atomic-scale impurities, twin boundaries other defects. Signals arise from superconductivity-enhanced Ruderman-Kittel-Kasuya-Yosida exchange coupling between impurity moments present normal discuss relevance these light recent experiments on interest.