Temperature dependence of the magnetic and electrical properties of Permalloy∕gadolinium∕Permalloy thin films

The magnetic and electrical properties of Permalloy∕gadolinium∕Permalloy (Py∕Gd∕Py) trilayers have been studied as a function of temperature by using vibrating sample magnetometer and transport measurements with current in plane configuration. The observed dependence of the magnetic moment with temperature can be explained by a paramagnetic contribution. Electrical measurements show that this contribution is originated by the formation of Gd1−xNix alloys at the Py∕Gd interfaces because of the Ni diffusion. Despite the Ni diffusion, we find no evidence of amorphization from either the Py layer or the Py∕Gd interfaces. We also obtain the Curie temperature of the Gd1−xNix alloys by the position of inflexion points in the resistance versus temperature curve.