Temperature-dependent periodicity of the persistent current in strongly interacting systems

TL;DR

This paper investigates how temperature affects the periodicity and magnitude of persistent currents in strongly interacting one-dimensional fermionic systems, revealing behaviors not explained by traditional models.

Contribution

It demonstrates that in the strongly interacting regime, persistent currents can change flux period and sign with temperature, highlighting phenomena missed by conventional theories.

Findings

Current can change from diamagnetic to paramagnetic with temperature

Magnitude of current can increase as temperature rises

Different decay rates of current depending on system polarization

Abstract

The persistent current in small isolated rings enclosing magnetic flux is the current circulating in equilibrium in the absence of an external excitation. While initially studied in superconducting and normal metals, recently, atomic persistent currents have been generated in ultracold gases spurring a new wave of theoretical investigations. Nevertheless, our understanding of the persistent currents in interacting systems is far from complete, especially at finite temperatures. Here we consider the fermionic one-dimensional Hubbard model and show that in the strong-interacting limit, the current can change its flux period and sign (diamagnetic or paramagnetic) as a function of temperature, features that cannot be explained within the single-particle or Luttinger liquid techniques. Also, the magnitude of the current can counterintuitively increase with temperature, in addition to presenting different rates of decay depending on the polarization of the system. Our work highlights the properties of the strongly-interacting multi-component systems which are missed by conventional approximation techniques, but can be important for the interpretation of experiments on persistent currents in ultracold gases.