Quantum criticality and confinement in weak Mott insulators

TL;DR

This paper investigates quantum phase transitions in two-dimensional models where electrons become charge-localized yet retain neutral excitations, revealing insights into quantum spin liquids and confinement phenomena.

Contribution

It introduces specific models demonstrating Mott transitions into quantum spin liquids and derives parent Hamiltonians for non-Abelian and $ ext{Z}_4$ quantum spin liquids.

Findings

Identification of models transitioning from superconducting or topological phases to insulators.

Analysis of neutral fermion confinement at symmetry-breaking transitions.

Derivation of coupled-wire Hamiltonians for exotic quantum spin liquids.

Abstract

Electrons undergoing a Mott transition may shed their charge but persist as neutral excitations of a quantum spin liquid (QSL). We introduce concrete two-dimensional models exhibiting this exotic behavior as they transition from superconducting or topological phases into fully charge-localized insulators. We study these Mott transitions and the confinement of neutral fermions at a second transition into a symmetry-broken phase. In the process, we also derive coupled-wire parent Hamiltonians for a non-Abelian QSL and a $\mathbb{Z}_4$ QSL.