Spontaneously orbital-selective superconductivity in a three-orbital Hubbard model

TL;DR

This paper investigates a three-orbital Hubbard model with negative Hund coupling, revealing spontaneous orbital-selective superconductivity and complex phase transitions relevant for alkali-doped fullerides.

Contribution

It demonstrates the emergence of an orbital-selective s-wave superconducting state in a three-orbital Hubbard model, expanding understanding of orbital-selective phenomena in strongly correlated systems.

Findings

Identification of two types of spontaneous orbital-selective Mott states

Discovery of an orbital-selective s-wave superconducting phase

Phase diagram detailing competition between ordered states

Abstract

We study a three-orbital Hubbard model with negative Hund coupling in infinite dimensions, combining dynamical mean-field theory with continuous time quantum Monte Carlo simulations. This model, which is relevant for the description of alkali-doped fullerides, has previously been shown to exhibit a spontaneous orbital selective Mott phase in the vicinity of the superconducting phase. Calculating the pair potential and double occupancy in each orbital, we study the competition between different homogeneous ordered states and determine the corresponding finite temperature phase diagram of the model. We identify two distinct types of spontaneous orbital-selective Mott states and show that an orbital-selective $s$-wave superconducting state with one superconducting and two metallic orbitals is spontaneously realized between the conventional $s$-wave superconducting phase and these two kinds of spontaneously orbital-selective Mott states.