Jang Hyuk-Jae, Appelbaum Ian
Center for Nanophysics and Advanced Materials and Department of Physics, University of Maryland, College Park, Maryland 20742 USA.
Phys Rev Lett. 2009 Sep 11;103(11):117202. doi: 10.1103/PhysRevLett.103.117202.
Using long-distance lateral devices, spin transport near the interface of Si and its native oxide (SiO(2)) is studied by spin-valve measurements in an in-plane magnetic field and spin precession measurements in a perpendicular magnetic field at 60 K. As electrons are attracted to the interface by an electrostatic gate, we observe shorter average spin transit times and an increase in spin coherence, despite a reduction in total spin polarization. This behavior, which is in contrast with the expected exponential depolarization seen in bulk transport devices, is explained using a transform method to recover the empirical spin current transit-time distribution and a simple two-stage drift-diffusion model. We identify strong interface-induced spin depolarization (reducing the spin lifetime by over 2 orders of magnitude from its bulk transport value) as the consistent cause of these phenomena.
