Temperature Dependence of the Lower Critical Field of the Noncentrosymmetric Superconductor α-BiPd

Temperature variation of the lower critical Hc1 field in the noncentrosymmetric superconductor alpha-BiPd is probed by local magnetization measurements using Hall micromagnetometry, performed down to 0.3 K in a magnetic field applied along the crystallographic b axis. Below a critical temperature Tc similar or equal to 3.8 K, a conventional Hc1(T) dependence is found, typical for a single-band s-wave superconductor. The obtained data imply an absence of spin-triplet component in the superconducting wavefunction and marginal multiband effects in this material, which contradicts some literature reports.