Superparamagnetism in Nanocrystalline Copper Ferrite Thin Films

Abstract

The rf sputtered copper ferrite films contain nanocrystalline grains. In these films, the magnetization does not saturate even in high magnetic fields. This phenomenon of high field susceptibility is attributed to the defects and/or superparamagnetic grains in the films. A simple model is developed to describe the observed high field magnetization behavior of these films. The model is found to fit well to the high field part for all the studied films. An attempt is also made to explain the temperature variation of the ferrimagnetic contribution on the basis of reported exchange constants.