Orbital Order, Metal Insulator Transition, and Magnetoresistance-Effect in the two-orbital Hubbard model

Abstract

We study the effects of temperature and magnetic field on a two-orbital Hubbard model within dynamical mean field theory. We focus on the quarter filled system, which is a special point in the phase diagram due to orbital degeneracy. At this particular filling the model exhibits two different long-range order mechanisms, namely orbital order and ferromagnetism. Both can cooperate but do not rely on each other's presence, creating a rich phase diagram. Particularly, in the vicinity of the phase transition to an orbitally ordered ferromagnetic state, we observe a strong magnetoresistance effect. Besides the low temperature phase transitions, we also observe a crossover between a paramagnetic insulating and a paramagnetic metallic state for increasing Hund's coupling at high temperatures.

7 pages, 7 figures

References in corpus (7)

• The numerical renormalization group method for quantum impurity systems
• Sum-rule Conserving Spectral Functions from the Numerical Renormalization Group
• A Numerical Renormalization Group approach to Green's Functions for Quantum Impurity Models
• Metal-Insulator phase diagram and orbital selectivity in 3-orbital models with rotationally invariant Hund coupling
• Structural relaxation due to electronic correlations in the paramagnetic insulator KCuF3
• Quantum Monte Carlo study for multiorbital systems with preserved spin and orbital rotational symmetries
• Itinerant ferromagnetism in the multiorbital Hubbard model: a dynamical mean-field study

Cited by in corpus (6)

• Strong electronic correlations from Hund's coupling
• Role of rotational symmetry in the magnetism of a multiorbital model
• Destabilization of ferromagnetism by frustration and realization of a nonmagnetic Mott transition in the quarter-filled two-orbital Hubbard model
• Orbital polaron in double exchange ferromagnets
• Improved estimator for numerical renormalization group calculations of the self-energy
• Mott transition, magnetic and orbital orders in the ground state of the two-band Hubbard model using variational slave-spin mean field formalism