A model of semimetallic behavior in strongly correlated electron systems

TL;DR

This paper introduces a modified Hubbard model incorporating hybridization to explain semimetallic behavior in strongly correlated electron systems, highlighting Coulomb interactions' role in transport anomalies.

Contribution

It extends the Hubbard model with hybridization to account for strong Coulomb repulsion, providing a theoretical framework for semimetallic behavior in correlated materials.

Findings

Transition from Mott insulator to metal with hybridization ('self-doping')

Model reproduces semimetallic behavior near the insulator transition

Transport property anomalies in Yb4As3 explained by Coulomb interactions

Abstract

Metals with values of the resistivity and the Hall coefficient much larger than typical ones, e.g., of sodium, are called semimetals. We suggest a model for semimetals which takes into account the strong Coulomb repulsion of the charge carriers, especially important in transition-metal and rare-earth compounds. For that purpose we extend the Hubbard model by coupling one additional orbital per site via hybridization to the Hubbard orbitals. We calculate the spectral function, resistivity and Hall coefficient of the model using dynamical mean-field theory. Starting from the Mott-insulating state, we find a transition to a metal with increasing hybridization strength (``self-doping''). In the metallic regime near the transition line to the insulator the model shows semimetallic behavior. We compare the calculated temperature dependence of the resistivity and the Hall coefficient with the one found experimentally for $\rm Yb_4As_3$. The comparison demonstrates that the anomalies in the transport properties of $\rm Yb_4As_3$ possibly can be assigned to Coulomb interaction effects of the charge carriers not captured by standard band structure calculations.