Effect of size on spin-transfer-driven ferromagnetic resonance in nanoscale magnetic tunnel junctions

ORAL

Abstract

Recently spin-transfer-driven ferromagnetic resonance (ST-FMR) has been explored to investigate the spin dynamics in various magnetic structures. ~For ST-FMR in a magnetic tunnel junction, an RF current at ferromagnetic resonance generates a sizable DC voltage across the tunnel junction [1], which provides a simple, yet effective means, to electrically detect the spin dynamics of the nanoscale free layer magnetization. In this talk, we present our measurements of ST-FMR for a set of MgO-based nanopillar magnetic tunneling junctions of different pillar aspect-ratios and sizes ranging from 65nm x 50nm to 170nm x 90nm. These data provide useful information to analyze the spin dynamics properties, such as damping and resonance conditions. Specifically, we found a strong dependence of the FMR condition on the cell size. ~Pronounced asymmetry in the spectra shape was observed for larger cells. ~The results may shed some light on boundary conditions for dipole-exchange spin waves in thin-film nanomagnets.[1]A. A. Tulapurkar et al., Nature 438, 339 (2005).

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Authors

  • Zhongming Zeng

    • Department of Physics \& Astronomy, University of California, Los Angeles, 90095

  • Kwun Hung Cheung

    • Department of Physics \& Astronomy, University of California, Los Angeles, 90095

  • Hongwen Jiang

    • Department of Physics \& Astronomy, University of California, Los Angeles, 90095
    • Department of Physics and Astronomy, University of California at Los Angeles
    • University of California, Los Angeles
    • UCLA

  • Ilya Krivorotov

    • Department of Physics \& Astronomy, University of California, Irvine, California 92697
    • University of California Irvine
    • University of California, Irvine

  • J.A. Katine

    • Hitachi Global Storage Technologies, San Jose, California 95135, USA