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Saturation of Spin-Polarized Current in Nanometer Scale Aluminum Grains

Y. G. Wei·C. E. Malec·D. Davidović
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Abstract

We describe measurements of spin-polarized tunnelling via discrete energy levels of single Aluminum grains. In high resistance samples ($\sim GΩ$), 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 $T_1^{-1}$ of the highest excited states is comparable to the electron tunnelling rate: $T_1^{-1}\approx 1.5\cdot 10^6 s^{-1}$ and $10^7s^{-1}$ in two samples. The ratio of $T_1^{-1}$ 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.

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Y. G. Wei, C. E. Malec, D. Davidović. 2007-10-29. Saturation of Spin-Polarized Current in Nanometer Scale Aluminum Grains. https://doi.org/10.1103/physrevb.76.195327

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