Itinerant ferromagnetism by eg and t2g states in the two-band Hubbard model

Abstract

Itinerant ferromagnetism derived fromeg and t2g states has been studied by the Gutzwiller variational method based on the two-band Hubbardmodel. The analysis shows that the magnetization value that depends on the orbitalreflects strength of renormalization for each band. As a result, the magnetization of the3d(t2g) band, which is more strongly renormalized in the calculation, has a larger value than that of the3d(eg) band. By changing the atomic interaction and projected orbital density of states(DOS), we have discussed general tendencies that the magnetizations by theeg and t2g states are determined by the relative intensities of the projected orbitalDOS at the Fermi energy, the renormalized kinetic energies relative toU, andstability of atomic multielectron configuration states. The result indicates that increases in Coulomb interactionU and the portion ofHund’s coupling J in the atomic interaction lead to balanced magnetizations between the two states. Variationin the above factors can generate a variety of spin-dependent electronic structures near theFermi energy in 3d transition metal ferromagnets.