Quantum phase transition between orbital-selective Mott states in Hund's metals

TL;DR

This paper uncovers a quantum phase transition between different orbital-selective Mott states in Hund's metals, highlighting the roles of charge fluctuations and spinless fermions, with implications for understanding correlated electron systems.

Contribution

It reveals a novel quantum phase transition in Hund's metals driven by charge fluctuations, distinct from magnetically-driven Mott transitions, using density matrix renormalization group methods.

Findings

Transition preempted by charge fluctuations and free spinless fermions

Universal Luttinger exponent in strong-coupling phase

Second transition from normal metal to intermediate phase at weak coupling

Abstract

We report a quantum phase transition between orbital-selective Mott states, with different localized orbitals, in a Hund's metals model. Using the density matrix renormalization group, the phase diagram is constructed varying the electronic density and Hubbard $U$, at robust Hund's coupling. We demonstrate that this transition is preempted by charge fluctuations and the emergence of free spinless fermions, as opposed to the magnetically-driven Mott transition. The Luttinger correlation exponent is shown to have a universal value in the strong-coupling phase, whereas it is interaction dependent at intermediate couplings. At weak coupling we find a second transition from a normal metal to the intermediate-coupling phase.