title: Unified description of bulk and interface-enhanced spin pumping.
abstract: We describe a mechanism for generating nonequilibrium electron-spin accumulation in semiconductors or metals by rf magnetic field pumping. With a semiclassical model we show that a rotating applied magnetic field (or the processing magnetization inside a weak ferromagnet) generates a dc spin accumulation. For bulk systems this spin accumulation is in general given by a small fraction of h omega, where omega is the rotation or precession frequency. With the addition of a neighboring, field-free region, and allowing for the diffusion of spins across the interface, the spin accumulation is dramatically enhanced towards h omega near the interface. The interface-enhanced spin accumulation obtained within our bulk-oriented model is surprisingly similar to predictions based on interface-scattering theory [A. Brataas, Phys. Rev. B 66, 060404(R) (2002)].
authors.affiliation: Physics of Nanodevices, Materials Science Centre, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands.
authors.forename: S M
authors.initials: SM
authors.lastname: Watts
authors.forename: J
authors.initials: J
authors.lastname: Grollier
authors.forename: C H
authors.initials: CH
authors.lastname: van der Wal
authors.forename: B J
authors.initials: BJ
authors.lastname: van Wees