Caloric and spin transport profile of Fermi-Hubbard systems


An open one-dimensional Fermi-Hubbard optical lattice exposed to external electromagnetic fields is investigated using the grand canonical ensemble formalism. As the system was reduced to a dimer, the eigenstates were determined using the exact diagonalization method while tuning the two-particle interactions of the lattice, a varying chemical potential, and applied external electromagnetic fields. Entropy and heat capacity gradients exist due to the interaction of the system with the external magnetic and electric fields, also known as magnetocaloric and electrocaloric effects, respectively. At particular temperatures, the isothermal entropic change was calculated to determine the necessary conditions for direct or inverse caloric effects to occur. The effects of more lattice sites and the elastic two-particle interaction can be incorporated through analytical methods. It was shown that at low temperatures, spins tend to scatter under the influence of repulsive two-particle interactions, while backflow occurs in the attractive regime. Furthermore, suitable temperature ranges for spin conductivity to occur can be found by adjusting the electromagnetic fields.