Theory of a continuous Mott transition in two dimensions

TL;DR

This paper develops a theoretical framework for the continuous Mott transition in two dimensions, revealing critical phenomena like a vanishing quasiparticle residue, diverging effective mass, and a universal resistivity jump at the quantum critical point.

Contribution

It introduces a detailed theory of the 2D Mott transition, characterizing the critical Fermi surface and associated non-Fermi liquid behavior, with predictions for universal resistivity jump and crossover phenomena.

Findings

Vanishing quasiparticle residue at transition

Diverging effective mass and Landau parameters

Universal resistivity jump at critical point

Abstract

We study theoretically the zero temperature phase transition in two dimensions from a Fermi liquid to a paramagnetic Mott insulator with a spinon Fermi surface. We show that the approach to the bandwidth controlled Mott transition from the metallic side is accompanied by a vanishing quasiparticle residue and a diverging effective mass. The Landau parameters $F^0_s, F^0_a$ also diverge. Right at the quantum critical point there is a sharply defined `critical Fermi surface' but no Landau quasiparticle. The critical point has a $Tln\frac{1}{T}$ specific heat and a non-zero $T = 0$ resistivity. We predict an interesting {\em universal resistivity jump} in the residual resistivity at the critical point as the transition is approached from the metallic side. The crossovers out of the critical region are also studied. Remarkably the initial crossover out of criticality on the metallic side is to a Marginal Fermi Liquid metal. At much lower temperatures there is a further crossover into the Landau Fermi liquid. The ratio of the two crossover scales vanishes on approaching the critical point. Similar phenomena are found in the insulating side. The filling controlled Mott transition is also studied. Implications for experiments on the layered triangular lattice organic material $\kappa-(ET)_2Cu_2(CN)_3$ are discussed.