Understanding multicaloric effects in anisotropic magnets via a mean-field approach

Abstract

Materials with magnetic anisotropy can serve as a model object for exploring the multicaloric effect because their thermodynamic state alterations can be achieved either through the application of a magnetic field H or/and by mechanically rotating the sample in the magnetic field using torque τ. In such materials, the total entropy change [Formula: see text] arises from two distinct contributions: (1) the conventional magnetocaloric effect (MCE) or paraprocess [Formula: see text] and (2) the rotational MCE [Formula: see text]. In this manuscript, using molecular field model which enables a separation of contributions to the total entropy change [Formula: see text] from conventional [Formula: see text] and rotational [Formula: see text], we have determined cross-coupling multicaloric coefficients [Formula: see text] and [Formula: see text] for anisotropic magnetic materials and show that they satisfy the basic thermodynamic identities. We also confirmed that the total multicaloric effect in the material with magnetic anisotropy can be accurately expressed as the sum of the individual magnetocaloric effects induced by separate application of the H and τ, minus the magnetic entropy change arising from thermodynamic cross-coupling between the subsystems of the solid: [Formula: see text].

Keywords

• Magnetocaloric effect
• magnetic anisotropy
• mean-field approach