Magnetic interactions between Mn and Co ions in oxides with perovskite structure
Ln <sub>1-y</sub>Sr <sub>y</sub>Мn <sub>1</sub>_ <sub>x</sub>.Со <sub>x</sub>O <sub>3</sub> compositions have been studied using neutron diffraction and magnetization measurements. The valence of cobalt ions increases from two to three as the cobalt content is growing. Trivalent cobalt is dominant in the low spinstate; however there is a small fraction of cobalt in the high spin state. Exchange interactions between Co <sup>3+</sup> (high spin state) and Mn <sup>4+</sup> ions are ferromagnetic and are similar in magnitude to positive exchange interactions between Co <sup>2+</sup> and Mn <sup>4+</sup> ions.