Noncentrosymmetric Superconductor BeAu

Noncentrosymmetric superconductors have attracted tremendous research interest due to the
possibility of mixed spin-singlet and spin-triplet pairing in these materials. In this work, physical
properties of the noncentrosymmetric superconductor BeAu were investigated. It was established
that BeAu undergoes a structural phase transition from a room-temperature noncentrosymmetric
FeSi structure type to a high-temperature CsCl structure type. The roomtemperature
modification undergoes a superconducting transition below T_c = 3.3 K. The values of
lower (H_c1 = 32 Oe) and upper (H_c2 = 335 Oe) critical field are rather small, confirming that
this Type II (κ_G-L = 2.3) weakly coupled (λ_e-p = 0.5, ΔC_e/γ_nT_c = 1.26) superconductor can be
well understood within the Bardeen-Cooper-Schriefer theory. The muon spin relaxation analysis
indicates that the time-reversal symmetry is preserved when the superconducting state is entered,
supporting conventional superconductivity in BeAu.