Abstract
He+ -ion irradiation resulted in the direct ordering of PtMn without postannealing. Samples were irradiated with 2 MeV He+ ions and a beam current of 1.08 μA cm2 such that the corresponding surface temperature was 190 °C. The exchange bias direction was set in situ during irradiation in a field of 900 Oe. A high giant magnetoresistance (GMR) ratio of 11% was obtained in PtMn -based spin valves after He+ irradiation. The GMR is completely eliminated after it is irradiated with oxygen ions at 42 keV. Combining He+ with oxygen-ion irradiation can provide magnetic patterning for GMR sensors. © 2006 American Institute of Physics.