F. Y. Yang

Publications (3)0 Total impact

• Article: Long-range FMR driven spin pumping through a nonmagnetic insulator

  Y. Pu, H. L. Wang, C. H. Du, R. Adur, A. J. Berger, A. Hauser, R. E. A. Williams, D. W. McComb, E. Johnston-Halperin, P. C. Hammel, F. Y. Yang
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  ABSTRACT: Ferromagnetic resonance (FMR) driven spin pumping is an emerging technique for injection of a pure spin current from a ferromagnet (FM) into a non-magnetic (NM) material without an accompanying charge current. It is widely believed that this pumping proceeds exclusively via a short-range exchange interaction at the FM/NM interface. Here we report robust, long-range spin pumping from the ferrimagnetic double perovskite Sr2FeMoO6 (SFMO) into Pt across an insulating barrier up to 200 nm thick, and systematically rule out all known spurious effects. This result demonstrates dynamic spin injection over a distance far beyond the coupling range of the exchange interaction, exposing the need to consider other coupling mechanisms. The characteristic length scale for magnetic textures in Sr2FeMoO6 is approximately 150 nm, resulting from structural antiphase boundaries, thus raising the possibility that magnetic dipole coupling underlies the observed long range spin transfer. This discovery reveals a route to dynamic angular momentum transfer between a FM and a NM in the absence of mediation by itinerant electrons and promises new spin-functional devices employing long-range spin pumping.
  05/2013;
• Source

  Available from: arxiv.org

  Article: Defect states and disorder in charge transport in semiconductor nanowires

  Dongkyun Ko, X W Zhao, Kongara M Reddy, O D Restrepo, R Mishra, I S Beloborodov, Nandini Trivedi, Nitin P Padture, W Windl, F Y Yang, E Johnston-Halperin
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  ABSTRACT: We present a comprehensive investigation into disorder-mediated charge transport in InP nanowires in the statistical doping regime. At zero gate voltage transport is well described by the space charge limited current model and Efros-Shklovskii variable range hopping, but positive gate voltage (electron accumulation) reveals a previously unexplored regime of nanowire charge transport that is not well described by existing theory. The ability to continuously tune between these regimes provides guidance for the extension of existing models and directly informs the design of next-generation nanoscale electronic devices.
  06/2011; 23.
• Source

  Available from: ArXiv

  Article: Growth control of GaAs nanowires using pulsed laser deposition with arsenic over pressure

  X. W. Zhao, T. R. Lemberger, F. Y. Yang
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  ABSTRACT: Using pulsed laser ablation with arsenic over pressure, the growth conditions for GaAs nanowires have been systematically investigated and optimized. Arsenic over pressure with As$_2$ molecules was introduced to the system by thermal decomposition of polycrystalline GaAs to control the stoichiometry and shape of the nanowires during growth. GaAs nanowires exhibit a variety of geometries under varying arsenic over pressure, which can be understood by different growth processes via vapor-liquid-solid mechanism. Single-crystal GaAs nanowires with uniform diameter, lengths over 20 $\mu$m, and thin surface oxide layer were obtained and can potentially be used for further electronic characterization.
  05/2007;