0825dissertacao Final Francisco Cesar

seu potencial magnetocalórico. Palavra-Chave: Efeito Magnetocalórico, Filme Fino e Hólmio iii ABSTRACT The Manetocaloric Effect has been discovered since 1881, is today the basis of the development of magnetic refrigeration systems. This is characterized by two quantities: the isothermal entropy change (∆SIsot.) and the adiabatic temperature change (∆TAdiab.), which are evaluated under variations in the intensity of an applied magnetic field. In the adiabatic process when the material is subjected to an external magnetic field, its temperature increases. Reversibly, when the field is removed, the temperature of magnetic material decreases until its initial value. In the isothermal process, the material is thermally insulated. Thus, the temperature of magnetic material does not change with the application of a magnetic field, but in contrast, gives off heat to the thermal reservoir. Removing the field, the material absorbs heat from the reservatory, remaining, however, at the same temperature. The effect is caused by the change in internal energy of the material and is intrinsic to any magnetic material, with its well characterized effect near the Curie temperature. In this work we present a study of the magnetocaloric effect considering the fundamental concepts about the theoretical formulation and the calculations procedures of the Thermodynamics, which describe the magnetocaloric potential. We also present a theoretical study on thin films of rare earth…