Evidence of ferromagnetic domains in the La_0.67Ca_0.33Mn_0.9Fe_0.1O₃ perovskite

Abstract

The nature of the low-temperature magnetic state of polycrystalline La_0.67Ca_0.33Mn_0.9Fe_0.1O₃ has been studied by magnetization, neutron diffraction, and neutron depolarization measurements. Neutron depolarization measurements indicate the existence of ferromagnetic domains with low net magnetic moments below 108 K. The substitution of Mn³⁺ by Fe³⁺ reduces the number of available hopping sites for the Mn e_g (up) electron and suppresses the double exchange, resulting in the reduction of ferromagnetic exchange. The competition between the ferromagnetic double-exchange interactions and the coexisting antiferromagnetic superexchange interactions and its randomness due to random substitutions of Mn³⁺ with Fe³⁺ drive the system into a randomly canted ferromagnetic state at low temperatures.