Anomalies of magnetic, electric and elastic properties of Sm 1− xSr xMnO 3 manganites due to phase separation

Abstract

Colossal magnetoresistance (MR) and giant negative volume magnetostriction (MS) have been observed in the Curie temperature region of Sm 1− x Sr x MnO 3 manganites for x=0.33 compounds containing ferromagnetic (FM) and A-type antiferromagnetic (AFM) clusters, and for x=0.4 and 0.45 containing FM and both types of AFM clusters (A type and charge ordering (CO) type). For x=0.33 magnetization, MR and MS increase smoothly with magnetic field increase and saturation of MR and MS is not achieved. For x=0.4 and 0.45 the sharp jump of magnetization, MR and MS takes place at H C1< H< H C2, and saturation is achieved at H> H C2. We believe that the reason for colossal MR and giant MS being observed in the investigated compounds is the increase of FM phase volume under magnetic field action. For x=0.33 this increase is smooth because it arises from the FM phase “sprouting” on FM layers of the A-type AFM phase. For x=0.4 and 0.45 the increase of FM part volume arises from CO clusters with CE type of AFM structure too. In this case, CO clusters are completely transformed to the FM state. This transition is accompanied by crystal structure reconstruction that is manifested in both the temperature and magnetic field dependences of the anisotropic MS.