Magnetic properties of cobaltites doped with chromium, gallium, and iron ions

The magnetic and magnetotransport properties of cobaltites La 0.5 Sr 0.5 Co 1– x Me x O 3 ( Me = Cr, Ga, Fe) have been studied. The initial compound ( x = 0) is a ferromagnet with T C = 247 K and a saturation magnetization close to 2μ B per formula unit. It has ben shown that chromium substitution ( x = 0.2) decreases the spontaneous magnetization to 0.3μ B , while the iron substitution ( x = 0.2) does not change the magnetization. The obtained data have been interpreted in a model of positive superexchange interactions between cobalt and iron and negative superexchange interactions between cobalt and chromium.