Comparative study of electronic structure of new superconductors (Sr,Ca)Pd2As2 and related compound BaPd2As2
I. A. Nekrasov+, M. V. Sadovskii+*
+Institute for Electrophysics UB of the RAS, 620016 Ekaterinburg, Russia
*Institute for Metal Physics UB of the RAS, 620990 Ekaterinburg, Russia
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 1 K 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.