Magnetization reversal in TmCr1−xCoxO3 perovskite solid solutions studied by Monte Carlo simulations

Abstract

In this work, we studied the magnetization reversal (MR) phenomenon in the perovskite solid solution TmCr1−xCoxO3, where magnetic Cr3+ ions were substituted by non-magnetic low-spin (LS) Co3+ ions. Magnetic measurements and Monte Carlo (MC) simulations were performed following a field-cooling (FC) protocol. Samples of TmCr1-xCoxO3 with 0.1 ≤ x ≤ 0.8 were synthesized and structurally characterized. Samples with 0.1 ≤ x < 0.5 were synthesized at 1200 °C in the air atmosphere, while those with 0.5 ≤ x ≤ 0.8 were synthesized at 1000 °C under high O2 pressure. A model was implemented to simulate the FC magnetization curves, taking into account the coupling between Tm3+ and Cr3+ ions. This model is based on a classical Heisenberg spin Hamiltonian with realistic interactions. We showed that it is possible to reproduce the MR phenomenon with MC simulations in perovskite oxides with magnetic rare earth and transition metal sublattices. MC simulations accurately described all the FC curves except for x = 0.6 because this composition is near the percolation threshold, where fluctuations in the distribution of Co3+ ions can alter the magnetic properties. Another explanation could be a possible spin reorientation of the Cr3+ ions sublattice that makes experimental magnetization depart from the predicted one. In addition, it was found that the antiferromagnetic superexchange interactions between Cr3+ ions increase with Co3+ content.