Formation of Magnetization Plateaus in Rare Earth Tetraborides: Exact Diagonalization and Quantum Monte Carlo Studies

Abstract

A relatively simple model based on the coexistence of spin and electron subsystems is proposed for a description of magnetization processes in metallic rare earth tetraborides. The model takes into account the Ising interaction between the localized spins, the Hubbard interaction between the itinerant electrons, and the Ising interaction between electron and spin subsystems. To solve this model, a combination of small cluster exact diagonalization calculations and quantum Monte Carlo simulations is used. Particular attention is paid to a description of correlation effects (the Hubbard interaction) on formation and stabilization of magnetization plateaus with fractional magnetizations. It is shown that the Hubbard interaction significantly stabilizes the 1/2 magnetization plateau and simultaneously suppresses the 1/3 magnetization plateau, in accordance with experimental measurements in rare earth tetraborides.