On the nature of the magnetocaloric effect of the first-order magnetostructural transition

Methods were developed to determine the structural entropy contribution to the total isothermal entropy change of materials which undergo a magnetostructural first-order phase transition. The structural entropies range from 4.5 to 45 J kg−1 K−1 and are proportional to the volume differences of the phases involved in the transition. This correlation allows one to predict new giant magnetocaloric effect materials from crystallographic data. There is a critical magnetic field which must be exceeded to drive the structural transition to completion.