Professor John Gregg

Abstract:

Giant magnetoresistive Co-Ag granular films are prepared by molecular beam epitaxy at three different temperatures with cobalt concentrations ranging from 30 to 80 at. %. The structural properties of these films are studied using a variety of diffraction techniques and real space probes. Magnetization and magnetotransport measurements are carried out at room temperature. Correlating the structural and magnetotransport properties reveals that the spin diffusion length strongly affects the amplitude of the giant magnetoresistance, which is otherwise dominated by the surface-to-volume ratio of the segregated magnetic precipitates. © 1996 The American Physical Society.

Abstract:

A new mechanism for spin channel mixing is discussed which contributes to the effective spin diffusion length in granular giant magnetoresistive materials. Two limiting cases are considered in which magnetic clusters act either to filter out the down component of the spin channel or cause the quantisation axis to precess.