In ballistic injection spin transport devices, a tunnel junction emitter bias voltage determines the energy at which spin-polarized hot electrons cross a Schottky barrier into the conduction band of a semiconductor collector. Fast energy relaxation via phonon emission restores equilibrium for subsequent transport at the band edge. Through an analysis incorporating voltage-dependent measurement of magnetocurrent polarization in silicon spin transport devices along with magnetic-tunnel- and spin-valve-transistor configurations, the contribution to total spin depolarization caused by this inelastic scattering in the presence of spin-orbit interaction is quantified. From the shape of this spectroscopy, it is found that all measured spin depolarization can be accounted for solely by considering spin relaxation during bulk transport in quasi-equilibrium near the conduction band edge; the relaxation of initial spin state is irrelevant to the spin-dependent device characteristics.
Bibliographical noteFunding Information:
This work was supported by the Office of Naval Research under contract N000141110637, the National Science Foundation under Contracts ECCS0901941 and ECCS1231855, and the Defense Threat Reduction Agency under Contract HDTRA1-13-1-0013. We acknowledge the support of the Maryland NanoCenter and its FabLab.
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