Magnetocaloric effect at the first-order magnetic phase transitions

On the basis of a thermodynamic approach, the magnetocaloric effect (MCE) arising at the first-order transition in heavy rare earth metals Tb, Dy, Er and Tb0.5Dy0.5 alloy and in Fe0.49Rh0.51 and Gd5Si1.7Ge2.3 is considered. The main contributions to the MCE (exchange, magnetoelastic, anisotropic and magnetic energy) were calculated in the temperature interval corresponding to the first-order transition. It is shown that the model adequately describes the MCE and gives results, which are in accord with the direct experimental measurements.