Professor John Gregg

Abstract:

We present magnetisation and giant magnetoresistance (GMR) measurements for MBE grown CoAg granular films with the external field applied parallel and perpendicular to the film plane. Both the magnetisation and the GMR show uniaxial anisotropy with the easy axis of magnetisation out-of-plane for Co concentrations of 30 at% and less and in the film plane for higher Co concentrations. We attribute this behaviour to the shape anisotropy of the magnetic particles in the films.

Abstract:

By exploiting the simplicity of a novel transport measurement on a ferromagnetic striped domain structure in a thin film of cobalt, we report the first direct observation of ferromagnetic domain wall scattering and what we believe to be the first clear indication of giant magnetoresistive effects (GMR) in a homogeneous magnetic system. A new model is proposed to describe these observations which highlights the crucial role played by electron spin precession in determining the electrical transport properties of magnetic interfaces.