Insight into the Magnetization Reversal and Exchange Bias in RFe<sub>0.5</sub>Cr<sub>0.5</sub>O<sub>3</sub> Ceramics
Li Hou, Lei Shi, Jiyin Zhao, Ruixue Tong, Xin Yang
Abstract
The R-dependent structural and magnetic properties of the disordered RFe0.5Cr0.5O3 (R = Ce, Pr, Nd, Sm) ceramics are systemically investigated. Based on the model composed of the paramagnetic R sublattice and the canted antiferromagnetic Fe/Cr sublattice, by estimating the temperature-dependent magnetizations of the samples, it is found that the moments of polarized Pr3+ and Nd3+ are antiparallel to the moment of Fe3+/Cr3+ in the compounds, which leads to the presence of magnetization reversal (MR) in NdFe0.5Cr0.5O3 or suppressed MR in PrFe0.5Cr0.5O3 due to the weak anisotropy, respectively. In addition, a giant positive (negative) exchange bias (EB) effect is observed distinctly in the R = Nd (Sm) compounds, which is attributed to the “pinning effect” of R on Fe/Cr spins due to the antiferromagnetic (ferromagnetic) coupling between the R and Fe/Cr sublattices. It is suggested that an intrinsic correlation exists between the MR and EB effects because of the magnetic interaction between the R and Fe/Cr sublattices. The sign of the EB field is determined by the competition between the Zeeman energy of the R3+ spins and the coupling energy between Fe/Cr and R sublattices. These results contribute to the physical mechanism of the MR and EB effects, which are useful for the practical applications of RFe0.5Cr0.5O3 ceramics.