Spin valve magnetoresistive sensor for high temperature environment using iridium managnese

A magnetoresistive (MR) read sensor fabricated on a substrate includes a ferromagnetic layer that is exchange coupled with an antiferromagnetic layer made of a defined composition of iridium manganese. A tantalum layer is used so that the exchange field and coercivity do not change with variations in annealing temperature. The antiferromagnetic layer is formed with a material composition of IrxMn100-x wherein x is in the range of 1523. In an embodiment of a spin valve structure, the tantalum layer is disposed over the substrate and the antiferromagnetic layer is in direct contact with a pinned ferromagnetic layer. In another embodiment, the IrMn layer is formed over a soft active layer. In a third embodiment using exchange pinning, spaced IrMn regions are formed over the active MR layer to define the sensor track width.