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 m agnetic thin films have been examined. Arrays of wires with equal mark/spac e ratios were patterned in resist using optical lithography. 100 nm thick N i80Fe15Mo5 films were partially or completely etched using broad beam ion m illing to assess the dependence of magnetic properties on the degree of int erconnection between the wires. These structures show a progressive increas e in coercivity and a transition between single and two-stage switching wit h increasing milling depth. A similar nanopatterning technique has been app lied to unpinned (Ni80Fe20/Cu/Ni80Fe20) spin valve structures in order to e nhance the coercivity of one of the ferromagnetic layers; the increased coe rcivity induced by patterning changes the natural similarity of the magneti c layers and the completed structure exhibits a small spin valve response.