Two-stage metal-insulator transition in the 2D Hubbard model: momentum selectivity in the 8-site dynamical cluster approximation

TL;DR

This study reveals a multi-stage, momentum-dependent metal-insulator transition in the 2D Hubbard model, showing intermediate phases with partial gapping and particle-hole asymmetry, using an 8-site dynamical cluster approximation.

Contribution

It demonstrates the momentum-sector specific nature of the transition and introduces the concept of a gradually shrinking Fermi arc or pocket in this context.

Findings

Multi-stage transition with momentum selectivity

Intermediate phase with coexisting gapped and gapless regions

Pronounced particle-hole asymmetry

Abstract

Metal-insulator transitions in the paramagnetic phase of the two dimensional square lattice Hubbard model are studied using the dynamical cluster approximation with eight momentum cells. We show that both the interaction-driven and the doping-driven transition are multi-stage and momentum-sector specific, with Fermi liquid metal and fully gapped insulator phases separated by an intermediate phase in which some regions of the Brillouin zone are gapped while others sustain gapless quasiparticles. We argue that this is the coarse-grained version of a gradually shrinking arc or pocket. A pronounced particle-hole asymmetry is found.