Novel Mott Transitions in Non-Isotropic Two-Band Hubbard Model

TL;DR

This paper investigates Mott transitions in a two-band Hubbard model with different subband widths, revealing complex phase behavior including two successive first-order transitions influenced by Hund's coupling.

Contribution

It introduces a detailed analysis of Mott transitions in a non-isotropic two-band Hubbard model using dynamical mean field theory, highlighting the effects of Hund's rule coupling.

Findings

Two successive first-order transitions with full Hund's coupling.

Lower transition remains first-order without spin-flip and pair-exchange.

Upper transition becomes continuous without spin-flip and pair-exchange.

Abstract

The Mott transition in a two-band Hubbard model involving subbands of different widths is studied as a function of temperature using dynamical mean field theory combined with exact diagonalization. The phase diagram is shown to exhibit two successive first-order transitions if the full Hund's rule coupling is included. In the absence of spin-flip and pair-exchange terms the lower transition remains first-order while the upper becomes continuous.