Metamagnetic behaviour in TbCo0.5Mn0.5O3.06 perovskite

Investigation of the crystal structure, magnetic ordering and magnetic properties of the compound TbCo0.5Mn0.5O3.06 has been carried out by neutron powder diffraction and magnetization measurements. The Co and Mn ions are shown to have a partial NaCl-type crystallographic ordering in the B- sublattice of the ABO(3) perovskite. On the basis of the magnetization study, metamagnetic behaviour has been revealed. The critical fields of the metamagnetic transition have been found to decrease with the approach to the Curie point at 98 K. The neutron diffraction experiments suggest that the compound TbCo0.5Mn0.5O3.06 consists of ferromagnetic and spin-glass-like phases. In the absence of an external magnetic field, a small ferromagnetic component appears in the Tb sublattice. The magnetic moments are directed antiparallel to the ferromagnetic component of the Co/Mn sublattice due to a negative f-d exchange polarization. Below 10 K a short-range antiferromagnetic order starts to develop in the Tb sublattice. The spin-glass- like phase associated with the random Co/Mn distribution transforms into the ferromagnetic phase under an external magnetic field, while in the Tb sublattice long-range magnetic order, being a superposition of the F, A, C, and G components, develops.