Multitude of phases in correlated lattice fermion systems with spin-dependent disorder

J Skolimowski,K Byczuk,D Vollhardt

doi:10.1088/2399-6528/aaae1b

Abstract

The magnetic phases induced by the interplay between disorder acting only on particles with a given spin projection (‘spin-dependent disorder’) and a local repulsive interaction is explored. To this end the magnetic ground state phase diagram of the Hubbard model at half-filling is computed within dynamical mean-field theory combined with the geometric average over disorder, which is able to describe Anderson localization. Five distinct phases are identified: a ferromagnetically polarized metal, two types of insulators, and two types of spin-selective localized phases. The latter four phases possess different long-range order of the spins. The predicted phase diagram may be tested experimentally using cold fermions in optical lattices subject to spin-dependent random potentials.

Highlights

Cold atoms in optical lattices provide an excellent experimental tool to explore the interplay between interaction and disorder effects in quantum many-body systems [1]
These developments motivated us to extend our previous work on correlated lattice fermions with spin-dependent disorder [16, 17] to the case with antiferromagnetic long-range order (AF-LRO)
The ground state of the Anderson-Hubbard model equation (1) with spin-dependent disorder on a bipartite lattice is determined by three factors: the strengths of the disorder and of the local repulsion, respectively, and the possible existence of AF-LRO

Summary

Introduction

Cold atoms in optical lattices provide an excellent experimental tool to explore the interplay between interaction and disorder effects in quantum many-body systems [1]. Together with a theoretically proposed new cooling method [14], this allows experiments with ultracold atoms to be performed at temperatures at which antiferromagnetic order in a finite system appears, i.e., where the correlation length reaches the size of the system [15] These developments motivated us to extend our previous work on correlated lattice fermions with spin-dependent disorder [16, 17] to the case with antiferromagnetic long-range order (AF-LRO). We show that two spin-selective localized phases with LRO exists One such phase extends to arbitrarily strong disorder, and the system remains metallic in one of the spin-subsystem, in contrast to the case studied earlier [19]. It has been used to examine the MIT in the paramagnetic, disordered Hubbard model at finite temperatures [35]

Model and method

Phase diagram

Conclusions and outlook