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PHYSICAL REVIEW B 84, 165318 (2011) Modeling spin transport in electrostatically-gated lateral-channel silicon devices: Role of interfacial
 

Summary: PHYSICAL REVIEW B 84, 165318 (2011)
Modeling spin transport in electrostatically-gated lateral-channel silicon devices: Role of interfacial
spin relaxation
Jing Li and Ian Appelbaum*
Department of Physics, Center for Nanophysics and Advanced Materials, University of Maryland, College Park, Maryland 20742, USA
(Received 11 August 2011; published 17 October 2011)
Using a two-dimensional finite-differences scheme to model spin transport in silicon devices with lateral
geometry, we simulate the effects of spin relaxation at interfacial boundaries, i.e., the exposed top surface and
at an electrostatically-controlled backgate with a SiO2 dielectric. These gate-voltage-dependent simulations are
compared to previous experimental results and show that strong spin relaxation, due to extrinsic effects, yields a
Si/SiO2 interfacial spin lifetime of 1 ns, orders of magnitude lower than lifetimes in the bulk Si. Relaxation
at the top surface plays no substantial role. Hall effect measurements on ballistically injected electrons gated
in the transport channel yield the carrier mobility directly and suggest that this reduction in spin lifetime is
only partially due to enhanced interfacial momentum scattering, which induces random spin flips as in the
Elliott effect. Therefore, other extrinsic mechanisms, such as those caused by paramagnetic defects should also
be considered in order to explain the dramatic enhancement in spin relaxation at the gate interface over bulk
values.
DOI: 10.1103/PhysRevB.84.165318 PACS number(s): 85.75.-d, 72.25.Dc, 72.25.Hg, 85.30.Tv
I. INTRODUCTION
In nonmagnetic materials, a nonequilibrium spin polariza-

  

Source: Appelbaum, Ian - Department of Physics, University of Maryland at College Park

 

Collections: Engineering; Materials Science