Irradiation-controlled giant magnetoresistance of PtMn-based spin valve

PtMn based spin valves showed a high giant magnetoresistance (GMR) ratio of 11 percent when irradiated with [He.sub.+] ions. The use of 42 keV O-ions for irradiating the same completely eliminated the GMR and significantly increased the resistance of the irradiated area thereby implying that a combination of [He.sub.+] and oxygen-ion radiation can provide magnetic patterning for GMR sensors.