Non-equilibrium magnetothermal effects in Ising dimers: relevance to the problem of low-temperature magnetic refrigeration

In this study, we analyze the thermal processes in Ising-type exchange-coupled binuclear clusters induced by the sudden switching off of an initially applied magnetic field. The main result is the established correlation between the sign of the exchange parameter and the sign of the thermal effect caused by the fast field switching off. We demonstrate that in the case of ferromagnetic Ising-type superexchange associated with easy-axis magnetic anisotropy, the spin system absorbs heat, resulting in the cooling of the surrounding. Conversely, in the case of antiferromagnetic exchange corresponding to easy-plane anisotropy, heat is released by the spin system, leading to heating. These results reveal a possibility to regard Ising-type dimers exhibiting ferromagnetic exchange as a class of low- and ultralow-temperature magnetic refrigerants with potential for practical applications. We also discuss the conditions under which such cooling could be most efficient.