Crystal structure, magnetic and elastic properties of Sr0,8Y0,2CoO2,65

Abstract

Communicated by Corresponding Member Fedor P. Korshunov

A comprehensive study of the crystal structure, magnetic and elastic properties of layered cobaltite Sr_0,8Y_0,2CoO_2,65 with a perovskite-type structure was carried out. It is established that the magnetic ordering in this composition is accompanied by a structural transition. The Neel temperature (T_N) is 375 K. The unit cell volume at TN increases as a result of the orbital ordering in the CoO₅ pyramids connected by the vertices in the anion-deficient layers. The main magnetic structure is an antiferromagnetic G-type structure with a small ferromagnetic component. The non-collinear magnetic structure is stabilized by the ferromagnetic bonds between the cobalt ions in the CoO₅ pyramids. Co³⁺ ions in the both layers are in the mixed low-spin (LS)/high-spin (HS) state. The temperature dependence of the electrical resistivity has a semiconductor character. The large resistivity value and small magnetoresistance indicate a good stability of the semiconductor antiferromagnetic state of this composition.