Electron-phonon superconductivity in non-centrosymmetric LaNiC$_2$: first principles calculations

TL;DR

This study uses first principles calculations to analyze the electronic structure and electron-phonon interactions in LaNiC$_2$, revealing it as a conventional superconductor with mixed pairing symmetry due to its non-centrosymmetric nature.

Contribution

First principles calculations demonstrating the electron-phonon mechanism and pairing symmetry in LaNiC$_2$, highlighting the role of specific phonon modes and lack of inversion symmetry.

Findings

LaNiC$_2$ is a conventional electron-phonon superconductor.

Two low frequency phonon modes significantly contribute to pairing.

The pairing exhibits dominant s-wave with some p-wave mixture.

Abstract

We report first principles calculations of the electronic structure and electron-phonon coupling in the non-centrosymmetric superconductor LaNiC$_2$. These show that the material is a conventional electron-phonon superconductor with intermediate coupling. There are large contributions to the coupling by two low frequency C non-bond-stretching modes, one of which has strong Kohn anomalies. Since LaNiC$_2$ lacks inversion symmetry, the pairing is of dominant s-wave type with some mixture of p-wave character. This will give exponential decay in the specific heat.