Adiabatic spin cooling using high-spin Fermi gases

TL;DR

This paper proposes a novel adiabatic cooling method for ultracold high-spin fermions by spatially redistributing entropy, potentially enabling better access to antiferromagnetic order in experiments.

Contribution

It introduces a new entropy redistribution technique using high-spin fermions with variable Zeeman coupling, specifically targeting spin degrees of freedom for cooling.

Findings

Spatial entropy can be concentrated in high-spin wings, cooling the spin-1/2 core.

Thermodynamic Bethe Ansatz and local density approximation reveal entropy distribution.

Method could facilitate access to antiferromagnetic order in ultracold fermion experiments.

Abstract

Spatial entropy redistribution plays a key role in adiabatic cooling of ultra-cold lattice gases. We show that high-spin fermions with a spatially variable quadratic Zeeman coupling may allow for the creation of an inner spin-1/2 core surrounded by high-spin wings. The latter are always more entropic than the core at high temperatures and, remarkably, at all temperatures in the presence of frustration. Combining thermodynamic Bethe Ansatz with local density approximation, we study the spatial entropy distribution for the particular case of one-dimensional spin-3/2 lattice fermions in the Mott phase. Interestingly, this spatially dependent entropy opens a possible path for an adiabatic cooling technique that, in contrast to previous proposals, would specifically target the spin degree of freedom. We discuss a possible realization of this adiabatic cooling, which may allow for a highly efficient entropy decrease in the spin-1/2 core and help access antiferromagnetic order in experiments on ultracold spinor fermions.