Antisite domains in double perovskite ferromagnets: Impact on magnetotransport and half-metallicity

Harish-Chandra Research Institute - Chhatnag Road, Jhusi, Allahabad 211019, India

^a pinaki@mri.ernet.in

Received: 22 November 2010
Accepted: 6 April 2011

Abstract

Several double perovskite materials of the form A₂BB ′ O₆ exhibit high ferromagnetic T_c, and significant low-field magnetoresistance. They are also a candidate source of spin-polarized electrons. The potential usefulness of these materials is, however, frustrated by mislocation of the B and B ′ ions, which do not organise themselves in the ideal alternating structure. The result is a strong dependence of physical properties on preparative conditions, reducing the magnetization and destroying the half-metallicity. We provide the first results on the impact of spatially correlated antisite disorder, as observed experimentally, on the ferromagnetic double perovskites. The antisite domains suppress magnetism and half-metallicity, as already known from studies of uncorrelated disorder, but lead to a dramatic enhancement of the low-field magnetoresistance.