Pressure-induced Superconductivity in Noncentrosymmetric Weyl Semimetals LaAlX (X = Si and Ge)

TL;DR

This study discovers pressure-induced superconductivity in noncentrosymmetric Weyl semimetals LaAlX (X=Si, Ge), revealing a dome-shaped phase diagram with potential for topological superconductivity without structural phase change.

Contribution

It reports the first observation of superconductivity in LaAlX under pressure, maintaining nontrivial topology and expanding understanding of superconductivity in Weyl semimetals.

Findings

Superconductivity appears at ~65 GPa in LaAlX without structural change.

Maximum Tc of 2.5 K for LaAlSi and 2.1 K for LaAlGe.

Nontrivial band topology persists up to 80.4 GPa.

Abstract

In topological materials, Dirac fermions can split into two Weyl fermions with opposite chiralities due to the breaking of space inversion symmetry, while in non-centrosymmetric superconductors, novel superconducting electron pairing mechanisms arise because of the antisymmetric spin-orbit coupling. In this work, we report the pressure-introduced superconductivity in a typical noncentrosymmetric Weyl semimetal LaAlX (X=Si and Ge). Superconductivity was observed at around 65 GPa without structural phase transition. A typical dome-shape phase diagram is obtained with the maximum Tc of 2.5 K (2.1 K) for LaAlSi (LaAlGe). Furthermore, the application of pressure does not destroy the nontrivial band topology of LaAlSi up to 80.4 GPa, making such materials as potential candidates for realizing topological superconductivity. Our discovery of superconductivity in LaAlX (X=Si and Ge) will provide critical insight in noncentrosymmetric superconductors and stimulate further study on superconductivity in Weyl semimetals.