Film thickness and width dependence of output voltage response for read-out head using induced RF permeability change

For thin film magnetic read-out heads using induced RF permeability change, named an Active Head by the authors, the relation between the output voltage response to magnetic fields and domain behavior involved was investigated with film thickness and width as parameters. With decreasing film width, the output voltage change decreased markedly, especially for films about 200nm thick, while B-H curves changed from closed curves to square curves and high-density Neel walls appeared. It has been demonstrated that the decrease in output voltage change is associated with the suppression of magnetization rotation, due to high-density Neel walls. However, films with high-density Bloch walls showed relatively large output voltage change, even with decreasing film width. Films without high-density Neel walls, such as 800nm thick films, are preferable for the high sensitivity narrow track Active Head.