Probing spin flip scattering in ballistic nanosystems...

Because spin-flip scattering length is longer than the electron mean-free-path in a metal, past studies of spin-flip scattering are limited to the diffusive regime. Spin accumulation in the nanometer sized spacer layer of a magnetic double barrier tunnel junction allows the study of spin flip scattering near ballistic limit. We extract the spin-flip conductance $G_s$ of the spacer layer from magnetoresistance measurements. A linear temperature dependence of $G_s$ is found. The bias voltage dependence shows a quantum well resonance which explains the sharp reduction of the magnetoresistance. At 4.2K $G_s$ yields the mean-free-path (70nm) and the spin-flip length ($1.0$-$2.6\mu$m).