Electronic Structure and Fermiology of Superconducting LaNiGa$_2$

TL;DR

This paper investigates the electronic structure and Fermi surface of LaNiGa$_2$, a superconductor with potential triplet pairing, revealing its three-dimensional metallic nature, weak to intermediate coupling strength, and non-magnetic Ni configuration.

Contribution

The study provides detailed electronic structure calculations and Fermi surface analysis of LaNiGa$_2$, highlighting its weak to intermediate coupling superconductivity and non-magnetic Ni state.

Findings

Fermi surface is three-dimensional with large sheets.

Superconducting coupling constant $eta$ is less than or equal to 0.55.

Ni is in a non-magnetic $d^{10}$ configuration.

Abstract

We report electronic structure calculations for the layered centrosymmetric superconductor LaNiGa$_2$, which has been identified as having a possible triplet state based on evidence for time reversal symmetry breaking. The Fermi surface has several large sheets and is only moderately anisotropic, so that the material is best described as a three dimensional metal. These include sections that are open in the in-plane direction as well as a section that approaches the zone center. The density of states is high and primarily derived from Ga $p$ states, which hybridize with Ni $d$ states. Comparing with experimental specific heat data, we infer a superconducting $\lambda \le$ 0.55, which implies that this is a weak to intermediate coupling material. However, the Ni occurs in a nominal $d^{10}$ configuration in this material, which places the compound far from magnetism. Implications of these results for superconductivity are discussed.