Phase separation in optical lattices in a spin-dependent external potential

TL;DR

This paper explores how spin-dependent external potentials induce phase separation in one-dimensional Fermi gases on optical lattices, revealing a critical interaction strength and the transition from Mott-insulating to ferromagnetic cores.

Contribution

It demonstrates the role of spin-dependent confinement and strong interactions in causing phase separation and phase transitions in 1D Fermi gases, using density-matrix renormalization.

Findings

Existence of a critical repulsive interaction strength for phase separation.

Transition from Mott-insulating to ferromagnetic insulating core with trap imbalance.

Phase separation driven by interplay of confinement and strong interactions.

Abstract

We investigate the phase separation in one-dimensional Fermi gases on optical lattices. The density distributions and the magnetization are calculated by means of density-matrix renormalization method. The phase separation between spin-up and spin-down atoms is induced by the interplay of the spin-dependent harmonic confinement and the strong repulsive interaction between intercomponent fermions. We find the existence of a critical repulsive interaction strength above which the phase separation evolves. By increasing the trap imbalance, the composite phase of Mott-insulating core is changed into the one of ferromagnetic insulating core, which is incompressible and originates from the Pauli exclusion principle.