Comparative Study of Electronic structure of New Superconductors (Sr,Ca)Pd2As2 and related compound BaPd2As2

TL;DR

This study compares the electronic structures of new superconductors (Sr,Ca)Pd2As2 and BaPd2As2 using LDA calculations, revealing differences from iron-based superconductors and suggesting doping could enhance their critical temperatures.

Contribution

It provides the first detailed electronic structure comparison of these Pd-based superconductors, highlighting how doping influences their density of states and potential Tc improvements.

Findings

Fermi surfaces are three-dimensional, unlike iron-based superconductors.

Doping increases the density of states at the Fermi level by about 2.5 times.

LDA calculations match experimental densities of states, indicating weak electronic correlations.

Abstract

This paper presents the comparative study of LDA calculated electronic structure of new isostructural to iron based systems superconductors (Sr,Ca)Pd2As2 with Tc about 1K and similar but structurally different system BaPd2As2. Despite chemical formula looks similar to iron superconductors and even main structural motif is the same - layers of Fe square lattices, electronic structure of (Sr,Ca)Pd2As2 and BaPd2As2 differs from Fe(As,Se)-HTSC completely. All these systems have essentially three dimensional Fermi surfaces in contrast to Fe(As,Se) materials. The Fermi level is crossed by low intensive tails of Pd-4d and As-4p states. However (Sr,Ca)Pd2As2 and BaPd2As2 materials have rather well developed peaks of Pd-4d(x2-y2) band. Thus by doping of about 2 holes per unit cell one can increase density of states at the Fermi level by a factor about 2.5. Since experimentally these compounds were found to be simple BCS superconductors the hole doping may considerably increase Tc. LDA calculated total densities of states at the Fermi level for stoichiometric systems perfectly agree with experimental estimates signifying rather small role of electronic correlations.