Magnetic transitions in strong coupling expansions for nearly degenerate states

Abstract

We consider a strong coupling expansion for a two-band Hubbard model on two sites with nearly degenerate states. A comparative analysis is performed for different schemes of perturbation theory which are applicable to systems with nearly degenerate states. A fourth order approach which builds on a four-dimensional low-energy subspace with nearly degenerate states captures accurately the transition from an antiferromagnetic to a ferromagnetic ground state at large on-site Coulomb interaction.

15 pages, 6 figures; version corrects typos and other minor mistakes

References in corpus (2)

• Microscopic origin of diagonal stripe phases in doped nickelates
• Orbital-selective Mott Transitions in a Doped Two-band Hubbard Model