Temperature dependence of the lower critical field of the noncentrosymmetric superconductor $\alpha$-BiPd

TL;DR

This study investigates how the lower critical magnetic field varies with temperature in the noncentrosymmetric superconductor α-BiPd, revealing conventional s-wave behavior and challenging previous claims of complex multiband or spin-triplet features.

Contribution

The paper provides detailed local magnetization measurements showing conventional s-wave superconductivity in α-BiPd, contradicting earlier reports of multiband or spin-triplet characteristics.

Findings

Hc1(T) follows a typical single-band s-wave BCS dependence

No evidence of spin-triplet component in the superconducting wavefunction

Indicates marginal multiband effects in α-BiPd

Abstract

Temperature variation of the lower critical field in the noncentrosymmetric superconductor $\alpha$-BiPd was 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 $T_c \simeq$ 3.8 K, a conventional $H_{c1}(T)$ dependence was found, typical for a single-band $s$-wave BCS 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.