THERMAL EFFECTS IN SMALL METALLIC PARTICLES

The process of thermally assisted switching in small metallic particles is studied by measuring the field dependent fluctuation fields. A correlation is found between the size of crystallographic sub-units rather than the total volume of the particles and the fluctuation Fields. Therefore, very small particles can be more stable magnetically than large particles, if they contain only few large crystal grains. The grain volumes are determined by X-ray line broadening measurements on random and on oriented samples. The effect of thermal activation on the switching process is confirmed by measuring the recording currents needed to optimize high frequency output in tape samples prepared with the same particles.