title: Dynamic detection of electron spin accumulation in ferromagnet-semiconductor devices by ferromagnetic resonance.
abstract: A distinguishing feature of spin accumulation in ferromagnet-semiconductor devices is its precession in a magnetic field. This is the basis for detection techniques such as the Hanle effect, but these approaches become ineffective as the spin lifetime in the semiconductor decreases. For this reason, no electrical Hanle measurement has been demonstrated in GaAs at room temperature. We show here that by forcing the magnetization in the ferromagnet to precess at resonance instead of relying only on the Larmor precession of the spin accumulation in the semiconductor, an electrically generated spin accumulation can be detected up to 300 K. The injection bias and temperature dependence of the measured spin signal agree with those obtained using traditional methods. We further show that this approach enables a measurement of short spin lifetimes (<100 ps), a regime that is not accessible in semiconductors using traditional Hanle techniques.
authors.affiliation: School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455, USA.
authors.forename: Changjiang
authors.initials: C
authors.lastname: Liu
authors.affiliation: Department of Materials, University of California, Santa Barbara, California 93106, USA.
authors.forename: Sahil J
authors.initials: SJ
authors.lastname: Patel
authors.affiliation: School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455, USA.
authors.forename: Timothy A
authors.initials: TA
authors.lastname: Peterson
authors.affiliation: School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455, USA.
authors.forename: Chad C
authors.initials: CC
authors.lastname: Geppert
authors.affiliation: School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455, USA.
authors.forename: Kevin D
authors.initials: KD
authors.lastname: Christie
authors.affiliation: School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455, USA.
authors.forename: Gordon
authors.initials: G
authors.lastname: Stecklein
authors.affiliation: Department of Materials, University of California, Santa Barbara, California 93106, USA.|Department of Electrical and Computer Engineering, University of California, Santa Barbara, California 93106, USA.
authors.forename: Chris J
authors.initials: CJ
authors.lastname: Palmstrøm
authors.affiliation: School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455, USA.
authors.forename: Paul A
authors.initials: PA
authors.lastname: Crowell