Increase of Curie temperature with La doping in the double perovskite Sr2-LayFeMoO6 within an electronic correlation approach

Abstract

The double perovskite compound Sr2FeMoO6 has a half-metallic ferromagnetic character and a
high Curie temperature (420 K). Fe-Mo usually present some degree of disorder in either Fe or
Mo ions, it is therefore fundamental to understand the role of electronic and structural parameters
controlling the half-metallic character together with a Curie temperature as high as possible. We replaced
divalent Sr2+ by trivalent La3+ ions in Sr2FeMoO6 system to observe the Curie temperature
behavior. We present an electronic approach using the Green's functions and the renormalization
perturbation expansion method, with localized Fe-spins and conduction Mo-electrons interacting
with the local spins via a double-exchange-type mechanism. We also include the electronic correlations
among the conduction electrons within a mean-eld approximation. Our results show
the density of states and the Curie temperature behavior when La concentration increases for the
Sr2y-yLayFeMoO6 system