Numerical study of magnetization processes in rare-earth tetraborides

Abstract

We present a simple model for a description of magnetization processes in rare-earth tetraborides. The model is based on the coexistence of two subsystems, and namely, the spin subsystem described by the Ising model and the electronic subsystem described by the Falicov-Kimball model on the Shastry-Sutherland lattice (SSL). Moreover, both subsystems are coupled by the anisotropic spin-dependent interaction of the Ising type. We have found, that the switching on the spin-dependent interaction ($J_z$) between the electron and spin subsystems and taking into account the electron hopping on the nearest ($t$) and next-nearest ($t'$) lattice sites of the SSL leads to a stabilization of new magnetization plateaus. In addition, to the Ising magnetization plateau at $m^{sp}/m_s^{sp}=1/3$ we have found three new magnetization plateaus located at $m^{sp}/m_s^{sp}=1/2$, 1/5 and 1/7 of the saturated spin magnetization $m_s^{sp}$. The ground-states corresponding to magnetization plateaus have the same spin structure consisting of parallel antiferromagnetic bands separated by ferromagnetic stripes.