Ferromagnetic resonance measurements of low magnetization damping in Co<sub>2</sub>FeAl films

ORAL

Abstract

Half-metallic Heusler compounds are predicted to have low intrinsic damping due to the suppression of spin-flip scattering. Here, we measure the damping constant in epitaxial MgO(001)/Co2FeAl Heusler films using broadband (0-40 GHz) ferromagnetic resonance (FMR). For in-plane FMR, the linewidth (~hundreds of Oe) is a nonlinear function of frequency and anisotropic, smaller for magnetization along CFA<110> and larger for magnetization along CFA <100>. A much narrower linewidth (~tens of Oe) is found for out-of-plane FMR, constraining the intrinsic damping value α≤10-3. The in-plane behavior of the FMR linewidth is attributed to an anisotropic two-magnon scattering mechanism. We follow the Krivosik’s approach (P. Krivosik et al. JAP 101, 083901 (2007)) to fit our in-plane linewidth data with a self-consistent two-magnon linewidth calculation and obtain an inhomogeneity correlation length of ~70nm with an intrinsic damping α≤10-3, which is consistent with the out-of-plane measurement. We discuss how the presence of low intrinsic damping enhances the two-magnon linewidth, explaining common reports of large two-magnon FMR linewidths in Heusler compounds.

*This work was supported by STARnet, a Semiconductor Research Cor-
poration program, sponsored by MARCO and DARPA.

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Presenters

  • Timothy Peterson

    • Physics and Astronomy, University of Minnesota

Authors

  • Timothy Peterson

    • Physics and Astronomy, University of Minnesota

  • W. Peria

    • Physics and Astronomy, University of Minnesota

  • Tao Qu

    • Electrical Engineering, University of Minnesota
    • University of Minnesota, Twin Cities
    • University of Minnesota

  • Anthony McFadden

    • Department of Electrical and Computer Engineering, University of California, Santa Barbara
    • Materials, University of California Santa Barbara

  • R. Victora

    • Electrical Engineering, University of Minnesota
    • University of Minnesota, Twin Cities

  • Chris Palmstrom

    • University of California Santa Barbara
    • Materials Department, California NanoSystems Institute, Electrical and Computer Engineering, University of California
    • University of California-Santa Barbara
    • California Nanosystems Institute, Dept. of Electrical and Computer Engineering, and Dept. of Materials, Univ of California - Santa Barbara
    • University of California - Santa Barbara
    • Electronics & Computer Enginneering, University of California Santa Barbara
    • Materials Department, University of California, Santa Barbara
    • Materials, University of California Santa Barbara
    • Univ of California - Santa Barbara

  • Paul Crowell

    • Physics and Astronomy, University of Minnesota
    • University of Minnesota
    • Univ of Minn - Minneapolis