Ground-state properties of fermionic mixtures with mass imbalance in optical lattices

Abstract

Ground-state properties of fermionic mixtures confined in a one-dimensional optical lattice are studied numerically within the spinless Falicov-Kimball model with a harmonic trap. A number of remarkable results are found. (i) At low particle filling the system exhibits the phase separation with heavy atoms in the center of the trap and light atoms in the surrounding regions.(ii) Mott-insulating phases always coexist with metallic phases. (iii) Atomicdensity waves are observed in the insulating regions for all particle fillings near half-filled lattice case. (iv) The variance of the local density exhibits the universal behavior (independent of the particle filling, the Coulomb interaction and the strength of a confining potential) over the whole region of the local density values.

Mixtures of fermionic atoms with mass imbalance in optical lattices

“…On the other hand, the regions of the atomic-density waves retain an insulating character also near half filling. Thus, in accordance with results obtained for the repulsive Falicov-Kimball model [15] we also find that in the attractive FalicovKimball model insulating domains coexist with metallic regions, such that global quantities are not appropriate to describe the system. With an even higher filling, the metallic phase in the center of the trap is further stabilized, but at some critical filling (N = 90) a new insulating phase ("a band insulator") starts to develop in the center of the trap ( = 1 = 1).…”

“…The last term is the energy of light and heavy atoms in the harmonic trapping potential of a strength V (for light atoms) and V (for heavy atoms). Very recently, we have performed exhaustive numerical studies of this model for repulsive interactions U > 0 and the same form of the trapping potential for both species of atoms [15]. We have found that the system exhibits the phase separation at low particle fillings.…”

Surmounting the sign problem in nonrelativistic calculations: A case study with mass-imbalanced fermions

“…Cases away from half filling were also studied in Refs. [23,24]. Furthermore, exact diagonalization studies have addressed harmonically trapped systems of up to 10 particles [25,26].…”

Vertex corrections to the electrical conductivity in models with elastically scattered electrons

“…The Falicov-Kimball model has been successfully applied to a simplified description of correlation-induced metalinsulator 7,8 and valence-change 9 transitions in rare-earth compounds, or atoms in optical lattices. 10,11 The disordered Anderson model has been used to describe the spectral and transport properties of metallic alloys 12 and vanishing of diffusion, called Anderson localization. 13 There have been efforts to describe the combined effect of electron correlations and randomness in the disordered Falicov-Kimball model 6 or Anderson localization in FKM.…”