Control of the switching properties of magnetic thin films and spin valve devices by patterning

The effects of patterning highly anisotropic repeating structures in soft magnetic thin films have been examined. Arrays of wires with equal mark/space ratios were patterned in resist using optical lithography. 100 nm thick Ni/sub 80/Fe/sub 15/Mo/sub 5/ films were partially or completely etched using broad beam ion milling to assess the dependence of magnetic properties on the degree of interconnection between the wires. These structures show a progressive increase in coercivity and a transition between single and two-stage switching with increasing milling depth. A similar nanopatterning technique has been applied to unpinned (Ni/sub 80/Fe/sub 20//Cu/Ni/sub 80/Fe/sub 20/) spin valve structures in order to enhance the coercivity of one of the ferromagnetic layers; the increased coercivity induced by patterning changes the natural similarity of the magnetic layers and the completed structure exhibits a small spin valve response.