Patent ID: 6927949

Claim:
A magnetic read head, comprising: a bottom magnetic shield; on said bottom magnetic shield, a first layer of aluminum oxide between about 80 and 120 Angstroms thick; on the first layer of aluminum oxide, a first layer of an insulating material having a thickness between about 40 and 60 Angstroms and a dielectric breakdown voltage that is as least 5 times that of aluminum oxide, said first aluminum oxide layer and the high voltage breakdown layer together constituting a lower dielectric layer whose total thickness is less than about 150 Angstroms; on the lower dielectric layer, a spin valve structure; on said spin valve structure a second layer of an insulating material having a thick-ness between about 40 and 60 Angstroms and a dielectric breakdown voltage that is at least 5 times that of aluminum oxide; on the second high voltage breakdown layer, a second layer of aluminum oxide having a thickness between about 80 and 120 Angstroms, the second aluminum oxide layer together with said second high breakdown layer constituting an upper dielectric layer whose thickness is between about 140 and 160 Angstroms; and on the upper dielectric layer, an upper magnetic shield layer whereby the magnetic read head has a minimum separation between its upper and lower magnetic shields that is less than 700 Angstroms.