The impact of dynamic nuclear polarization on non-local spin valve and inverse spin Hall Hanle measurements in n-GaAs

ORAL

Abstract

Non-local spin valve (NLSV) and inverse spin Hall (ISHE) Hanle measurements are important tools to probe spin-transport parameters such as the spin lifetime and spin Hall angle. We carried out such measurements on Fe/n-GaAs heterostructure samples with varying doping (3x1016 to 7x1016 cm-3) and at temperatures from 2 K to 110 K. The Hanle curves are very sensitive to the hyperfine field generated by dynamic nuclear polarization (DNP). Below a threshold temperature that depends on doping, the hyperfine field leads to distortion of the Hanle line-shapes for both NLSV and ISHE measurements and can enhance the ISHE signal by one order of magnitude. We have developed a pulsed-current technique which utilizes the vast difference between electron and nuclear spin relaxation time scales (about ns and s respectively) to eliminate the impact of the steady-state hyperfine field, and the obtained Hanle curves then match expectations based on simple drift-diffusion models. We will discuss the extracted spin lifetime and spin Hall angle, numerical modeling of the Hanle curves and the role of the hyperfine field in enhancing the apparent spin Hall signal.

*This work was supported by NSF DMR-1708287 and the NSF National Nano Coordinated Infrastructure Network (NNCI) under Award Number ECCS-1542202

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Presenters

  • Zhen Jiang

    • School of Physics and Astronomy, University of Minnesota, Twin Cities

Authors

  • Zhen Jiang

    • School of Physics and Astronomy, University of Minnesota, Twin Cities

  • Sahil Patel

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

  • Paul Crowell

    • School of Physics and Astronomy, University of Minnesota, Twin Cities
    • School pf Physics and Astronomy, University of Minnesota
    • University of Minnesota

  • Chris J Palmstrom

    • Materials Department, University of California, Santa Barbara
    • UCSB
    • Departments of Electrical and Computer Engineering and Materials, University of California, Santa Barbara
    • Dept. of Electrical Engineering, Univ. of California, Santa Barbara, CA, USA
    • Univ. of California, Santa Barbara
    • Electrical and Computer Engineering Department, University of California, Santa Barbara
    • University of California, Santa Barbara
    • IEE, UC Santa Barbara
    • University of California Santa Barbara
    • Univ of California, Santa Barbara
    • Electrical and Computer Engineering, University of California Santa Barbara
    • Materials and Electrical & Comp. Eng, University of California, Santa Barbara