  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.
