Polarization-induced phase separation and re-entrant transition of two component-fermions in a one-dimensional lattice

TL;DR

This paper investigates phase separation and re-entrant transitions in one-dimensional two-component fermions using the Bethe ansatz, revealing non-monotonic compressibility and polarization-induced phase changes.

Contribution

It introduces a detailed analysis of polarization effects on phase behavior in 1D fermionic systems using the Hubbard model and Bethe ansatz.

Findings

Compressibility is non-monotonic with polarization.

Phase separation occurs at intermediate interactions and polarization.

Re-entrant transition into mixed phase at higher polarization.

Abstract

By investigating the compressibility of one-dimensional lattice fermions at various filling factors, we study the phase separation and re-entrant transition within the framework of the Bethe ansatz method. We model the system using the repulsive Hubbard model and calculate compressibility as a function of polarization for arbitrary values of chemical potential, temperature, and interaction strength. For filling factors $ 0 < n < 1$, compressibility is a non-monotonic function of polarization at all thermodynamic parameters. The compressibility reveals a phase transition into a phase-separated state for both low and intermediate temperatures at intermediate interactions as one increases the polarization. For certain filling factors, we find the re-entrant transition into the mixed phase at a higher polarization.