Temperature-Induced Metal-Insulator Transition in a Narrow-Band Model with Non-Equivalent Hubbard Subbands at Half-Filling

TL;DR

This paper investigates how temperature can induce a metal-insulator transition in a narrow-band Hubbard model with non-equivalent subbands, highlighting the role of correlated hopping in this transition.

Contribution

It extends previous zero-temperature studies by analyzing temperature effects and demonstrates the importance of correlated hopping in metal-insulator transitions.

Findings

Energy gap widens with increasing temperature.

Transition from metal to insulator occurs at specific temperatures.

Correlated hopping lowers the transition temperature.

Abstract

In the previous papers (Journ. of Phys. Stud. 2, 362 (1998); cond-mat/9811213) we have studied metal-insulator transition in a generalized Hubbard model with correlated hopping at half-filling and zero temperature. The present paper is devoted to a further study of metal-insulator transition in this model,in particular, an investigation of temperature-induced metal-to-insulator transition. The dependence of energy gap on concentration of doubly occupancy leads to increasing energy gap width with increase of temperature. Thus narrow-band system can undergo transition from a metallic state to an insulating state with the increase of temperature. For some values of intra-atomic Coulomb repulsion $U$ and $w_0$ ($w_0$ is half-bandwidth) we find the values of temperature when narrow-band material undergoes transition from a metallic state to an insulating state. We show that at given $U/w_0$ metal-insulator transition in model with non-equivalent Hubbard sub-bands can occur at smaller temperature than in the Hubbard model. It testifies on the fact that taking into account of correlated hopping is important for a consideration of metal-insulator transition problem.