Electronic properties of bilayered manganite Ca2.5 Sr0.5 GaMn2 O8 from first-principles calculations

Abstract

By means of first-principles calculations using spin-polarized generalized gradient approximation method and ultrasoft pseudopotentials, the electronic and magnetic structure of the recently synthesized orthorhombic phase of bilayer manganite Ca2.5 Sr0.5 GaMn2 O8 compound is obtained. Our calculations have shown that the specific antiferromagnetic ordering, in accordance with experimental findings, is the most stable one. The total energies calculated for the several possible magnetic states of the title compound in the orthorhombic phase enable us to estimate spin exchange interactions for nearest Jnn =-1.60 meV and next- nearest neighbors Jnnn =-0.21 meV. Calculated Curie-Weiss temperature in the mean-field approximation is in excellent agreement with the measured magnetic phase transition temperature. © 2008 The American Physical Society.