Magnetoresistance and magnetic properties of Fe/Cu/Fe/GaAs(100)

A procedure for growth of smooth As free Fe surfaces on (4X6)-GaAs(100) is presented. Ferromagnetic resonance (FMR) revealed that the Fe films have an isotropies equal to bulk Fe, modified only by interface anisotropies. The F e films served as templates for the growth of epitaxial Fe/Cu/Fe trilayers which were subsequently characterized by FMR, magneto-optical Kerr effect, and magnetoresistance. At room temperature, films coupled through a 13.2-ML Cu spacer exhibited 2.0% giant magnetoresistance and 0.3% anisotropic magn etoresistance. The results showed that the interlayer exchange coupling for a 13.2-ML Cu spacer could not be described by bilinear and biquadratic con tributions alone. A different coupling, which varied as cosine cubed of the angle between the magnetizations of the Fe films, was required to explain the data (bicubic exchange coupling).