Electrical Control of Ultrafast Magnetic Speeds in Graphene Spin Field-Effect Junctions

ORAL

Abstract

Electric-field control of ultrafast magnetic processes is a key to low-energy, high-speed spintronics. The talk will describe graphene spin-field-effect junctions that enable gate-tunable superdiffusive spin transport across graphene-ferromagnet interfaces, providing an electrical knob for femtosecond magnetization dynamics. By electrostatically shifting the graphene Fermi level beneath a cobalt thin film, we tune interfacial spin-current transmission and thereby the laser-induced demagnetization time, reducing it from 203 fs (bare Co) to 93 fs, a more than 100% increase in the rate of magnetization quenching at fixed excitation. Superdiffusive-transport calculations reproduce the dependence on interface conductance and cobalt thickness, supporting a mechanism of enhanced angular-momentum transfer into graphene. The spin-field-effect junctions provide a route to gate-controlled ultrafast magnetic dynamics in device-relevant architectures.

*We gratefully acknowledge funding from the European Research Council (ERC) Project SPINNER (Grant No. 101002772), Stiftelsen Olle Engkvist Byggmästare (Grant No. 200–0602), the Swedish Research Council VR (Grants No. 2021-05932 and No. 2024-05531), and the Knut and Alice Wallenberg Foundation (Grants No. 2022.0079 and No. 2023.0336). Numerical calculations were enabled by resources from the National Academic Infrastructure for Supercomputing in Sweden (NAISS) at NSC Linköping, partially funded by VR through Grant Agreement No. 2022-06725. A. B. gratefully acknowledges financial assistance from the S. N. Bose National Centre for Basic Sciences (SNBNCBS), India (Project No. SNB/AB/11-12/96) and the Department of Science and Technology (DST), Government of India (Grant No. DST/NM/TUE/QM-3/2019-1C-SNB). S. M. acknowledges DST, India, for financial support from the INSPIRE fellowship.

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Publication: Muradas-Belinchón, D., et al., "Gate-tunable ultrafast spin-field-effect junctions," Phys. Rev. Lett. 135, 097001 (2025).

Presenters

  • David Muradas-Belinchón

    • Department of Physics and Astronomy, Uppsala University, Box 516, Uppsala SE-751 20, Sweden
    • Uppsala University

Authors

  • David Muradas-Belinchón

    • Department of Physics and Astronomy, Uppsala University, Box 516, Uppsala SE-751 20, Sweden
    • Uppsala University

  • Suchetana Mukhopadhyay

    • Department of Condensed Matter and Materials Physics, S. N. Bose National Center for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700106, India

  • Francesco Foggetti

    • Department of Physics and Astronomy, Uppsala University, Box 516, Uppsala SE-751 20, Sweden

  • Surya N Panda

    • Department of Condensed Matter and Materials Physics, S. N. Bose National Center for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700106, India

  • Olof Karis

    • Department of Physics and Astronomy, Uppsala University, Box 516, Uppsala SE-751 20, Sweden

  • Peter M Oppeneer

    • Department of Physics and Astronomy, Uppsala University, Box 516, Uppsala SE-751 20, Sweden
    • Uppsala University
    • Department of Physics and Astronomy, Uppsala University, Box 516, SE-75120 Uppsala, Sweden

  • Anjan Barman

    • Department of Condensed Matter and Materials Physics, S. N. Bose National Center for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700106, India

  • M. VENKATA KAMALAKAR

    • Department of Physics and Astronomy, Uppsala University, Box 516, Uppsala SE-751 20, Sweden
    • Uppsala University