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

Abstract

In this article we analyze thermal processes in the Ising-type exchange-coupled binuclear clusters induced by sudden switching off 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 cooling of the surroundings. Conversely, in the case of antiferromagnetic exchange corresponding to easy-plane anisotropy, heat is released by the spin system leading to heating. These results reveals a possibility to regard Ising type dimers exhibiting ferromagnetic exchange as a class of low-temperature magnetic refrigerants with potential for practical applications. We also discuss the conditions under which such cooling could be most efficient.