Temperature Dependence of Hysteresis Loops of NI Films-Characteristics of Fine-Grained Structure

Ni films, about 50 nm thick, prepared by de magnetron sputtering were investigated by magnetic measurements with an alternating gradient magnetometer in the temperature range 30 K -300 K. Films that were deposited at room temperature have a lower saturation magnetization than those deposited at higher temperature. The coercivity and remanence of the films increases with decreasing temperature. This is explained by that the films comprise various fractions of multi-domain and single-domain particles, including superparamagnetic ones.