Orbital-selective Mott transitions in the anisotropic two-band Hubbard model at finite temperatures

TL;DR

This study investigates orbital-selective Mott transitions in an anisotropic two-band Hubbard model at finite temperatures, revealing two distinct transitions even without spin-flip Hund exchange, using advanced quantum Monte Carlo methods.

Contribution

The paper demonstrates the occurrence of two orbital-selective Mott transitions in the anisotropic two-band Hubbard model without spin-flip Hund exchange, using high-precision dynamical mean-field theory calculations.

Findings

Two distinct orbital-selective Mott transitions identified

Second transition observed in low-frequency self-energy analysis

Transitions occur even without spin-flip Hund exchange

Abstract

The anisotropic degenerate two-orbital Hubbard model is studied within dynamical mean-field theory at low temperatures. High-precision calculations on the basis of a refined quantum Monte Carlo (QMC) method reveal that two distinct orbital-selective Mott transitions occur for a bandwidth ratio of 2 even in the absence of spin-flip contributions to the Hund exchange. The second transition -- not seen in earlier studies using QMC, iterative perturbation theory, and exact diagonalization -- is clearly exposed in a low-frequency analysis of the self-energy and in local spectra.