Orbital-Selective Mott transition out of band degeneracy lifting

TL;DR

This paper proposes a general mechanism for the orbital-selective Mott transition driven by band degeneracy lifting, applicable to various materials, and explains its connection to non-Fermi-liquid behavior and critical doping phenomena.

Contribution

It introduces a novel mechanism for OSMT based on crystal field splitting and degeneracy differences, expanding understanding of correlated electron systems.

Findings

OSMT can occur in bands with identical width and correlation if degeneracy is split.

The phase exhibits Curie-Weiss susceptibility and non-Fermi-liquid behavior.

Critical doping suppresses the OSMT phase, resembling pnictide physics.

Abstract

We outline a general mechanism for Orbital-selective Mott transition (OSMT), the coexistence of both itinerant and localized conduction electrons, and show how it can take place in a wide range of realistic situations, even for bands of identical width and correlation, provided a crystal field splits the energy levels in manifolds with different degeneracies and the exchange coupling is large enough to reduce orbital fluctuations. The mechanism relies on the different kinetic energy in manifolds with different degeneracy. This phase has Curie-Weiss susceptibility and non Fermi-liquid behavior, which disappear at a critical doping, all of which is reminiscent of the physics of the pnictides.