Orbital-selective Mott transitions in a doped two-band Hubbard model with crystal field splitting

TL;DR

This paper explores how crystal field splitting influences orbital-selective Mott transitions in a doped two-band Hubbard model, revealing new phases and non-Fermi-liquid behavior through advanced numerical and analytical methods.

Contribution

It uncovers a novel orbital-selective Mott phase of the wide band induced by crystal field splitting, expanding understanding of correlated electron systems.

Findings

Identification of a wide-band OSMP at strong interactions and specific crystal fields.

Demonstration of non-Fermi-liquid behavior in the wide-band OSMP.

Phase diagram mapping at moderate doping without magnetic or orbital order.

Abstract

We investigate the effects of crystal field splitting in a doped two-band Hubbard model with different bandwidths within dynamical mean-field theory (DMFT), using a quantum Monte Carlo impurity solver. In addition to an orbital-selective Mott phase (OSMP) of the narrow band, which is adiabatically connected with the well-studied OSMP in the half-filled case without crystal field splitting, we find, for sufficiently strong interaction and a suitable crystal field, also an OSMP of the wide band. We establish the phase diagram (in the absence of magnetic or orbital order) at moderate doping as a function of interaction strength and crystal field splitting and show that also the wide-band OSMP is associated with non-Fermi-liquid behavior in the case of Ising type Hund rule couplings. Our numerical results are supplemented by analytical strong-coupling studies of spin order and spectral functions at integer filling.