Thermally stable spin valve films with synthetic antiferromagnet pinned byNiMn for recording heads beyond 20 Gbit/in.(2)

The thermal stability of spin valve films with synthetic antiferromagnet (S AF) pinned by antiferromagnetic IrMn, NiO, and NiMn layers were studied. Th e SAF layer enhances the thermal stability in general; however, the blockin g temperature (and the blocking temperature distribution) of the antiferrom agnet is still important for the magnetic rigidity of the pinned layer. Onc e the temperature reaches the blocking temperature the SAF layer can go int o either the spin flip or flop state, depending upon the magnetic moment ra tio of the reference layer and pinned layers. The GMR linear head response can be distorted for nonlinearity. The NiMn pinned SAF structure shows magn etic and thermal stability which makes it practical for the real products. A high GMR of 11% can be obtained in both bottom and top NiMn SAF spin valv es by advanced processes. Recording heads were built using such stacks whic h demonstrated recording areal density of 20 Gbit/in.(2) and beyond. (C) 20 00 American Institute of Physics. [S0021-8979(00)73408-6].