Magnetic phase diagrams of the Ln(Mn1−xCox)O3 (Ln=Eu, Nd, Y) systems

Abstract

We report magnetization measurements in the Ln(Mn1−xCox)O3+λ (Ln=Eu, Nd; 0⩽x<1) and Y(Mn1−xCox)O3 (0.35⩽x⩽0.5) perovskites as a function of temperature and magnetic field. Compositions in the range of 0.35⩽x⩽0.8 (Ln=Eu), 0.4⩽x⩽0.6 (Ln=Nd), and 0.35⩽x⩽0.45 (Ln=Y) exhibit metamagnetic behavior associated with a transformation of the magnetic structure from ferrimagnetic, where the magnetic moments of Co2+ and Mn4+ ions are antiparallel, to ferromagnetic where they are parallel. A ferromagnetic state is observed for the 0.1⩽x⩽0.15 (Ln=Nd) and 0.45<x⩽0.5 (Ln=Y) compositions. Doping and H-T phase diagrams are presented, and these diagrams resemble those of Ln1−xCaxMnO3 charge-ordered manganites. Neutron diffraction studies indicate site ordering of the Co and Mn ions in the Y(Co0.5Mn0.5)O3 system, which is presumably responsible for its ferromagnetic behavior.