Unconventional superconductivity of BeAu

Unusual superconducting properties of the noncentrosymmetric compound BeAu have recently attracted a considerable amount of attention. While type-II superconductivity was initially reported in this material [1], it was later shown that the compound is in fact a type-I superconductor [2]. In-depth muon spin rotation, relaxation, and resonance (μSR) experiments have revealed that the time reversal symmetry is preserved in BeAu [2]. Furthermore, precise measurements of the thermodynamic critical field via μSR technique have indicated that its evolution as a function of temperature cannot be described within a single-gap scenario [3]. Instead, the data can be successfully fitted using a self-consistent two-gap approach. Additionally, a joint analysis of specific heat and μSR data has indicated that the superconductivity of BeAu is non-BCS-like [4]. This work illustrates that unconventional superconductivity of BeAu could only be revealed by using a joint analysis of several thermodynamic quantities.

[1] A. Amon et al., Physical Review B 97, 014501 (2018)
[2] J. Beare et al., Physical Review B 99, 134510 (2019)
[3] R. Khasanov et al., Physical Review Research 2, 023142 (2020)
[4] R. Khasanov et al., Physical Review B 102, 014514 (2020)