Bi-Layer Permalloy Films Grown in Orthogonal Applied Fields

Permalloy bi-layers grown in orthogonal applied fields demonstrated unusual coupling phenomena in Kerr-effect observations. The films were grown by UHV ion-beam sputtering in an applied field of 28 Oe that established a well-defined anisotropy direction. Mid-way through the deposition, the substrates were rapidly turned 90° in the applied field, inducing an orthogonal anisotropy direction in the second layer of the film. With layers of equal thickness, a simple model predicts the bi-layer to be isotropic in the plane of the film, regardless of the strength or mechanism of any interlayer coupling. Instead, the initial layer acquired the anisotropy orientation of the second layer grown. This unusual coupling was investigated for a number of bi-layer structures of different thicknesses. © 1990 IEEE