High magnetocaloric efficiency of a NiFe/NiCu/CoFe/MnIr multilayer in a small magnetic field

Abstract

The isothermal magnetic entropy changes Delta S (i.e., the magnetocaloric potential) are studied in Ni80Fe20/Ni67Cu33/Co90Fe10/Mn80Ir20 stacks at temperatures near the Curie point of the Ni67Cu33 spacer by applying magnetic fields of a few milli-Tesla. Such fields were sufficient for toggling magnetic moments in the soft ferromagnetic layer ( Ni80Fe20). It is found that this switching provides a significant enhancement of Delta S in the heterostructure system with respect to that achieved in a single Ni67Cu33 film under such weak magnetic fields. Our finding is believed to have the potential to be utilized in magnetocaloric devices (e.g., thin-film coolers) that would be based on ferromagnetic/paramagnetic/ferromagnetic heterostructures and would operate with moderate magnetic fields.