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arXiv · 1011.2250

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

Robert Peters·Norio Kawakami·Thomas Pruschke
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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.

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Robert Peters, Norio Kawakami, Thomas Pruschke. 2011-03-28. Orbital Order, Metal Insulator Transition, and Magnetoresistance-Effect in the two-orbital Hubbard model. https://doi.org/10.1103/physrevb.83.125110

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