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

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