Electronic Griffiths phase of the d=2 Mott transition

TL;DR

This paper explores how disorder affects the two-dimensional Mott transition, revealing a Griffiths phase characterized by strong local fluctuations and a distribution of quasiparticle weights, akin to infinite randomness fixed points.

Contribution

It demonstrates the emergence of an electronic Griffiths phase in 2D Mott transitions with disorder, contrasting high-dimensional behavior and linking to quantum magnetism concepts.

Findings

Disorder preserves Mott transition features at weak levels.

Local quasiparticle weights exhibit a broad distribution near criticality.

A Griffiths phase emerges before the metal-insulator transition.

Abstract

We investigate the effects of disorder within the T=0 Brinkman-Rice (BR) scenario for the Mott metal-insulator transition (MIT) in two dimensions (2d). For sufficiently weak disorder the transition retains the Mott character, as signaled by the vanishing of the local quasiparticles (QP) weights Z_{i} and strong disorder screening at criticality. In contrast to the behavior in high dimensions, here the local spatial fluctuations of QP parameters are strongly enhanced in the critical regime, with a distribution function P(Z) ~ Z^{\alpha-1} and \alpha tends to zero at the transition. This behavior indicates a robust emergence of an electronic Griffiths phase preceding the MIT, in a fashion surprisingly reminiscent of the "Infinite Randomness Fixed Point" scenario for disordered quantum magnets.