A non-shielded MR head with improved resolution

Although it has been generally assumed that to improve the resolution of an MR head, either the head must have a magnetic shield or its structure must be changed, we have succeeded in developing a non-shielded MR head with high track density, high sensitivity, low cross talk and much improved short wavelength characteristics. In the new head, only the very edge of the MR stripe is effectively biased, keeping the spacing loss low. Because MR film requires no anisotropy, and because a large permanent magnet embedded in the guard substrate is used to generate the bias field, the structure of the head can be simple. Sapphire is used as the substrate in order to minimize thermal noise. An Al2O3Tic (0.01Ω.cm resistivity) guard substrate is used to improve reliability.