Pauli paramagnetism of an ideal Fermi gas

TL;DR

This paper proposes a method to measure the magnetic susceptibility of a two-component ultracold Fermi gas using trapped atoms, demonstrating the approach with non-interacting $^6$Li and exploiting tunable interactions near Feshbach resonances.

Contribution

It introduces a novel experimental technique to directly measure magnetic susceptibility in ultracold atomic gases via density profiles.

Findings

Successfully measured susceptibility versus magnetic field in $^6$Li gas.

Demonstrated the ability to reach high polarization states in the atomic cloud.

Provided insights into Pauli paramagnetism in an ideal Fermi gas.

Abstract

We show how to use trapped ultracold atoms to measure the magnetic susceptibility of a two-component Fermi gas. The method is illustrated for a non-interacting gas of $^6$Li, using the tunability of interactions around a wide Feshbach resonances. The susceptibility versus effective magnetic field is directly obtained from the inhomogeneous density profile of the trapped atomic cloud. The wings of the cloud realize the high field limit where the polarization approaches 100%, which is not accessible for an electron gas.