Evidence for the coexistence of time-reversal symmetry breaking and Bardeen-Cooper-Schrieffer-like superconductivity in La7Pd3

Time-reversal symmetry breaking (TRSB) with a Bardeen-Cooper-Schrieffer (BCS)-like superconductivity occurs in a small, but growing number of noncentrosymmetric (NCS) materials, although the mechanism is poorly understood. We present heat capacity, magnetization, resistivity, and muon spin resonance/relaxation (mu SR) measurements on polycrystalline samples of NCS La7Pd3. Transverse-field mu SR and heat capacity data show La7Pd3 is a type-II superconductor with a BCS-like gap structure, while zero-field mu SR results provide evidence of TRSB. We discuss the implications of these results for both the La7X3 (where X = Ni, Pd, Rh, Ir) group of superconductors and other CS and NCS superconductors for which TRSB has been observed.

Automated summary

The study presents evidence of time-reversal symmetry breaking (TRSB) and Bardeen-Cooper-Schrieffer (BCS)-like superconductivity in noncentrosymmetric La7Pd3, suggesting implications for other CS and NCS superconductors where TRSB has been observed.