Magnetic properties of the orthoferrites TbFeO3 and ErFeO3

Abstract

The magnetic properties of the single-crystalline orthoferrites TbFeO3 and ErFeO3 were investigated by using a vibrating sample magnetometer (VSM). Both ferrites exhibit weak ferromagnetism with the maximum saturated moment being 0.125 and 0.054 mu(B)/Fe for TbFeO3 and ErFeO3, respectively. We confirmed the spin reorientation transition (SRT) in both systems. These two ferrites display different temperature-dependent behaviors of the magnetization, which we analyzed within the molecular field model. The results suggest that the Fe 3d-Er 4f magnetic coupling through the molecular field of the ordered Fe net moment is unexpectedly antiferromagnetism, opposite to the ferromagnetic Fe 3d-Tb 4f coupling. Further, the coupling widely varies with temperature and/or with the SRT, indicating that the Tb/Er moment is not simply explained by the partial polarization of the paramagnetic spins experiencing the molecular field of the net Fe moment.