Strong antisymmetric spin-orbit coupling and superconducting properties: The case of noncentrosymmetric LaPtSi

TL;DR

This study investigates how strong antisymmetric spin-orbit coupling influences superconductivity in LaPtSi, revealing a dominant spin-singlet pairing and challenging its potential for topological superconductivity.

Contribution

It provides experimental evidence that strong ASOC in LaPtSi results in conventional s-wave superconductivity, contradicting expectations of unconventional behavior.

Findings

LaPtSi exhibits dirty s-wave superconductivity.

Strong ASOC does not induce unconventional pairing in LaPtSi.

LaPtSi is unlikely to host topological superconductivity.

Abstract

In this work we aim to analyze the effect of a strong antisymmetric spin-orbit coupling (ASOC) on superconductivity of noncentrosymmetric LaPtSi. We study the energy gap structure of polycrystalline LaPtSi by using magnetic penetration depth measurements down to 0.02$T_c$. We observed a dirty s-wave behavior, which provides compelling evidence that the spin-singlet component of the mixed pairing state is highly dominant. This is consistent with previous results in the sense that the mere presence of a strong ASOC does not lead to unconventional behaviors. Our result also downplays LaPtSi as a good candidate for realizing time-reversal invariant topological superconductivity.