Ultrafast Spin-to-Charge Conversion in Topological-insulator/Ferromagnet Heterostructures

ORAL

Abstract

Strong spin-orbit coupling, resulting in the formation of spin-momentum-locked surface states in topological insulators (TIs), is predicted to possess superior spin-to-charge conversion (SCC) efficiency via the inverse Rashba-Edelstein effect and/or inverse spin Hall effect. The knowledge of the timescale of such SCC processes is crucial for the optimization of TI-based spintronic devices. Here, we investigate the ultrafast SCC in topological-insulator/ferromagnet heterostructures via terahertz emission spectroscopy. We demonstrate highly-efficient THz emission from Bi2Se3/Co heterostructures, where the surface states play a dominant role. Compared to the instantaneous shift current terahertz emission mechanism in Bi2Se3, we directly observe a temporal delay in the spin-current-related component — 0.12 ps, which characterizes the SCC timescale in TIs. In addition, we show that the SCC efficiency is temperature independent in Bi2Se3 as expected from the nature of the surface states. Our study provides fundamental insights into the ultrafast SCC processes, and demonstrate the practical applications of TIs, especially the surface states, in terahertz spintronic devices at room temperature.

–

Presenters

  • Xinbo Wang

    • Division of Physics and Applied Physics, Nanyang Technological University

Authors

  • Xinbo Wang

    • Division of Physics and Applied Physics, Nanyang Technological University

  • Liang Cheng

    • Division of Physics and Applied Physics, Nanyang Technological University
    • School of Physical and Mathematical Sciences, Nanyang Technological University

  • Dapeng Zhu

    • Department of Electrical and Computer Engineering, National University of Singapore
    • Dept. of Electrical and Computer Engineering, National Univ. of Singapore

  • Yang Wu

    • Department of Electrical and Computer Engineering, National University of Singapore

  • Mengji Chen

    • Department of Electrical and Computer Engineering, National University of Singapore

  • Daming Zhao

    • Division of Physics and Applied Physics, Nanyang Technological University

  • Jian-Xin Zhu

    • Center for Integrated Nanotechnologies, Los Alamos National Laboratory
    • Los Alamos National Laboratory
    • Los Alamos National Laboratory, Theoretical Division
    • Theoretical Division, Los Alamos National Laboratory
    • Los Alamos Natl Lab

  • Justin Song

    • Nanyang Technological University
    • Division of Physics and Applied Physics, Nanyang Technological University
    • School of Physical and Mathematical Sciences, Nanyang Technological University

  • Marco Battiato

    • Institute of Solid State Physics, Vienna University of Technology

  • Hyunsoo Yang

    • National University of Singapore
    • Department of Electrical and Computer Engineering, National University of Singapore
    • Dept. of Electrical and Computer Engineering, National Univ. of Singapore
    • Electrical and Computer Engineering, National University of Singapore

  • Ee Min Chia

    • Division of Physics and Applied Physics, Nanyang Technological University
    • School of Physical and Mathematical Sciences, Nanyang Technological University
    • Division of Physics and Applied Physics, Nanyang Tech Univ