Electronic structure of the 344-type superconductors La3(Ni;Pd)4(Si;Ge)4 by ab initio calculations

TL;DR

This study uses ab initio calculations to analyze the electronic structures of 344-type superconductors, revealing similarities in Fermi surfaces and suggesting a common phonon mechanism for their superconductivity.

Contribution

First comprehensive ab initio analysis comparing electronic structures of La3(Ni;Pd)4(Si;Ge)4 superconductors and their non-superconducting counterpart, highlighting similarities in Fermi surfaces.

Findings

Fermi surfaces contain both holelike and electronlike sheets with nesting properties.

Similar densities of states at the Fermi level across compounds.

Indications of a common phonon-mediated superconductivity mechanism.

Abstract

Electronic structures of superconducting ternaries: La3Ni4Si4, La3Ni4Ge4, La3Pd4Si4, La3Pd4Ge4, and their non-superconducting counterpart, La3Rh4Ge4, have been calculated employing the full-potential local-orbital method within the density functional theory. Our investigations were focused particularly on densities of states (DOSs) at the Fermi level with respect to previous experimental heat capacity data, and Fermi surfaces (FSs) being very similar for all considered here compounds. In each of these systems, the FS originating from several bands contains both holelike and electronlike sheets possessing different dimensionality, in particular quasi-two-dimensional cylinders with nesting properties. A comparative analysis of the DOSs and FSs in these 344-type systems as well as in nickel (oxy)pnictide and borocarbide superconductors indicates rather similar phonon mechanism of their superconductivity.