Anisotropy and Coercivity in Thin Films

Abstract

An arbitrary classification on thin films into three types may be made on the basis of the relative values of the anisotropy field, $H_K$ , and the intrinsic coercive force of the material, $H_I$ . These three types are (A) $H_K{\mathrm{>H}}_1\text{=0}$ , (B) $H_K\text{=0}$ ; $H_I\text{≠0}$ , and (C) $H_I{\mathrm{>H}}_K\text{≠0}$ . In case (A) the magnetization will seek the easy direction in the absence of an applied field and the film will have a rectangular hysteresis loop in the easy direction only. Certain films have isotropic magnetic properties in all directions. The magnetization in such films will remain in any direction to which it is moved by a field larger than the coercive force. These films are therefore classified as $H_K\text{=0}$ films. The third type of film has rectangular hysteresis loops in all directions but different apparent coercive forces, $H_F$ , in different directions.