Phase diagram of orbital-selective Mott transitions at finite temperatures

TL;DR

This paper explores the phase diagram of orbital-selective Mott transitions in a two-orbital Hubbard model at finite temperatures, revealing coexistence regions and the influence of Hund coupling on the transitions.

Contribution

It provides a systematic analysis of the finite-temperature phase diagram of OSMT, highlighting the role of Hund coupling and identifying new coexistence regions.

Findings

Identification of two coexistence regions at finite temperatures.

Discovery of a new coexistence region with three states at U=U' and J=0.

Establishment of the global phase diagram showing Hund coupling effects.

Abstract

Mott transitions in the two-orbital Hubbard model with different bandwidths are investigated at finite temperatures. By means of the self-energy functional approach, we discuss the stability of the intermediate phase with one orbital localized and the other itinerant, which is caused by the orbital-selective Mott transition (OSMT). It is shown that the OSMT realizes two different coexistence regions at finite temperatures in accordance with the recent results of Liebsch. We further find that the particularly interesting behavior emerges around the special condition $U=U'$ and J=0, which includes a new type of the coexistence region with three distinct states. By systematically changing the Hund coupling, we establish the global phase diagram to elucidate the key role played by the Hund coupling on the Mott transitions.