Unconventional metal-insulator transition in two dimensions

TL;DR

This paper demonstrates that the two-dimensional Mott transition in a simple model can be unconventional, resembling a Kosterlitz-Thouless transition, with strong electron interactions leading to anomalous critical properties and singular spectral behavior.

Contribution

It introduces a novel perspective on the 2D Mott transition, linking it to vortex-like unbinding phenomena and collective plasmon interactions, which was not previously established.

Findings

The transition is similar to a Kosterlitz-Thouless transition.

Insulating phase shows singular power-law behavior in spectra.

Electrons interact strongly with collective plasmon excitations.

Abstract

We show, by using a correlated Jastrow wave function and a mapping onto a classical model, that the two-dimensional Mott transition in a simple half-filled one-band model can be unconventional and very similar to the binding-unbinding Kosterlitz-Thouless transition of vortices and anti-vortices, here identified by empty and doubly occupied sites. Within this framework, electrons strongly interact with collective plasmon excitations that induce anomalous critical properties on both sides of the transition. In particular, the insulating phase is characterized by a singular power law behavior in the photoemission spectrum, that can be continuously connected to the fully-projected insulating state, relevant to strongly correlated low-energy models.