Analysis on three-sublattice model of magnetic properties in rare-earth iron garnets under high magnetic fields

摘要

In this paper, based on the molecular field theory, a new and improved three-sublattice model on studying the magnetic properties of ferrimagnetic rare-earth iron garnet in high magnetic fields is introduced. Here, the effective exchange field is described as H_i = λM = λχH_e, where A. is the coefficient associated with the molecular field, χ is the effective magnetic susceptibility, and H_e is external magnetic fields. As is known, the magnetic sublattices in rare-earth iron garnets can be classified three kinds labeled as a, c and d, in our calculations, whose magnetizations are defined as M_a, M_c and M_d, respectively. Then, using this model, the temperature and field dependences of the total magnetization in Dy_3Fe_5O_(12) (DyIG) are discussed. Meanwhile, the magnetizations of the three kinds of magnetic sublattices are analyzed. Furthermore, our theory suggests that the coefficients α_i associated with λ and χ in DyIG show obvious anisotropic, temperature-dependence and field-dependence characteristics. And, the theoretical calculations exactly fit the experimental data.