Time-Reversal Symmetry Breaking in Re-Based Kagome Lattice Superconductor

Abstract

We investigated the Re-based kagome superconductor Re${}_2$Zr through various measurements, including resistivity, magnetization, specific heat, and muon spin rotation and relaxation spectroscopy. These results suggest that Re${}_2$Zr is a moderately coupled potential two-gap superconductor. Zero-field muon relaxation data indicate the possible presence of a time-reversal symmetry-breaking state in the superconducting ground state. Our investigation identifies Re${}_2$Zr as a new unconventional superconductor with a potential complex order parameter that warrants considerable experimental and theoretical interest.

9 pages, 6 figures