Local moments and magnetic order in the two-dimensional Anderson-Mott transition

TL;DR

This paper investigates how electronic correlations influence the Anderson-Mott transition in a disordered 2D system, revealing local magnetic moments form and order prior to the Mott transition, with implications for magnetic and glassy states.

Contribution

It introduces a variational wave function approach that captures both Anderson and Mott insulating behaviors, including magnetic ordering and metastable spin-glass states in disordered 2D systems.

Findings

Local magnetic moments form and order before the Mott transition.

Charge gap opening correlates with vanishing compressibility fluctuations.

Frustrating hopping leads to metastable spin-glass states.

Abstract

We study the role of electronic correlation in a disordered two-dimensional model by using a variational wave function that can interpolate between Anderson and Mott insulators. Within this approach, the Anderson-Mott transition can be described both in the paramagnetic and in the magnetic sectors. In the latter case, we find evidence for the formation of local magnetic moments that order before the Mott transition. The charge gap opening in the Mott insulator is accompanied by the vanishing of the $\lim_{q\to 0} \overline{< n_q>< n_{-q}>}$ (the bar denoting the impurity average), which is related to the compressibility fluctuations. The role of a frustrating (second-neighbor) hopping is also discussed, with a particular emphasis to the formation of metastable spin-glass states.