BICRYSTAL CLUSTER STRUCTURE AND MAGNETIC-PROPERTIES OF COCRTA CR THIN-FILM MEDIA/

Structures of bicrystal clusters of CoCrTa thin film media are examine d using high resolution transmission electron microscopy (HRTEM), and the effects of the bicrystal clusters on magnetic hysteresis were stud ied using micromagnetic simulation. The bicrystal cluster of CoCrTa co nsists of two crystal lographic variants grown on a single Cr underlay er grain with their c axes normally-aligned in the film plane. The typ ical number of grains in each cluster is 2 to 3. With the bicrystal st ructure, coercivity decreases significantly as grain size decreases wh en intergranular exchange coupling is strong, and high hysteresis squa reness can be obtained. Coercivity in the small grain size region can be increased by reducing the exchange coupling.