We describe measurements of spin-polarized tunnelling via discrete energy levels of single Aluminum grains. In high resistance samples (∼GΩ), the spin-polarized tunnelling current rapidly saturates as a function of the bias voltage. This indicates that spin-polarized current is carried only via the ground state and the few lowest in energy excited states of the grain. At the saturation voltage, the spin-relaxation rate T1−1 of the highest excited states is comparable to the electron tunnelling rate: T1−1≈1.5⋅106s−1 and 107s−1 in two samples. The ratio of T1−1 to the electron-phonon relaxation rate is in agreement with the Elliot-Yafet scaling, an evidence that spin-relaxation in Al grains is governed by the spin-orbit interaction.
@article{arxiv.cond-mat/0703139,
title = {Saturation of Spin-Polarized Current in Nanometer Scale Aluminum Grains},
author = {Y. G. Wei and C. E. Malec and D. Davidović},
journal= {arXiv preprint arXiv:cond-mat/0703139},
year = {2009}
}