The permeability of one of the first and second shield layers in a read head is greater than the permeability of the other of the first and second shield layers for providing a net image current field HIM which can be employed for counterbalancing other fields acting on a free layer structure in a spin...http://www.google.com.au/patents/US6525911?utm_source=gb-gplus-sharePatent US6525911 - Permeability offset of shield layers for correcting bias of a free layer structure in a spin valve sensor
