Spin-selective localization of correlated lattice fermions

Abstract

The interplay between local, repulsive interactions and disorder acting only on one spin orientation of lattice fermions ("spin-dependent disorder") is investigated. The nonmagnetic disorder vs. interaction phase diagram is computed using Dynamical Mean-Field Theory in combination with the geometric average over disorder. The latter determines the typical local density of states and is therefore sensitive to Anderson localization. The effect of spin-dependent disorder is found to be very different from that of conventional disorder. In particular, it destabilizes the metallic solution and leads to a novel spin-selective, localized phase at weak interactions and strong disorder.

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

“…This is due to the breaking of the spin symmetry and, thus, the blocking of spin-flip processes which are responsible for quasiparticle formation. Moreover, a spin-selective localized phase was predicted [16]. In this phase the particles with spin direction sensitive to randomness are localized, whereas particles in the opposite spin channel remain itinerant.…”

“…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).…”

“…Here 'spin-dependent disorder' means that disorder, i.e., randomly distributed local potentials, acts only on fermions with one particular spin direction [16][17][18]. Our previous studies showed that spin-dependent disorder strongly destabilizes the metallic phase.…”

“…In this phase the particles with spin direction sensitive to randomness are localized, whereas particles in the opposite spin channel remain itinerant. The earlier studies of correlated lattice fermions with spin-dependent disorder [16][17][18] focused on paramagnetic phases, i.e., phases without spontaneous long-range order (LRO). Thus the question remained whether, and to what extent, AF-LRO of the fermions will change these results.…”

“…Thus the question remained whether, and to what extent, AF-LRO of the fermions will change these results. In particular, two questions arise: (1) How does the possible existence of AF-LRO modify the paramagnetic ground state phase diagram of interacting fermions with spin-dependent disorder [16]?…”