Reduced spin injection at high DC current in lateral spin valves

ORAL

Abstract

We report on non-local transport measurements in all metal lateral spin-valves with transparent contacts. We use direct current to investigate the symmetry in the injection process between a ferromagnet (FM) and a normal metal (NM). At high currents (around 1-2$\times $10$^{7}$A/cm$^{2})$ the non-local spin valve (NLSV) signal becomes larger when electrons are injected from the FM into the NM. A systematic study of the NLSV signal for different device lengths as a function of current magnitude and direction reveals the origin of this asymmetry. By fitting the near-exponential decay of the signal with distance the effects of FM polarization and NM spin diffusion length can be separated. These results show that the spin diffusion length of the NM is independent of current direction. However, the effective spin polarization of the FM appears to be larger when electrons are injected from FM into NM and smaller when electrons move in opposite direction. Possible explanations for this behavior will be discussed.

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Authors

  • Mikhail Erekhinsky

    Physics Department, UC San Diego

  • Amos Sharoni

    Department of Physics, Bar-Ilan University, Ramat-Gan 52900, Israel, Department of Physics, Bar Ilan University, Ramat Gan 52900, Israel, Bar Ilan University, Ramat Gan, Israel

  • Felix Casanova

    CIC nanoGUNE, San Sebastian (Basque Country)

  • Ivan K. Schuller

    Physics Department, University of California-San Diego, La Jolla California 92093-0319, USA, Department of Physics, University of California-San Diego, La Jolla, California 92093-0319, USA, Physics Department, UC San Diego, Department of Physics, University of California San Diego, La Jolla, CA 92093, University of California, San Diego, Physics Dept., Univ. of California San Diego