THERMAL EFFECTS IN SMALL METALLIC PARTICLES

The process of thermally assisted switching in small metallic particle s is studied by measuring the field dependent fluctuation fields. A co rrelation is found between the size of crystallographic sub-units rath er than the total volume of the particles and the fluctuation Fields. Therefore, very small particles can be more stable magnetically than l arge particles, if they contain only few large crystal grains. The gra in volumes are determined by X-ray line broadening measurements on ran dom and on oriented samples. The effect of thermal activation on the s witching process is confirmed by measuring the recording currents need ed to optimize high frequency output in tape samples prepared with the same particles.