Coherent spin-phonon oscillations and demagnetization dynamics in the van der Waals ferromagnet CrI<sub>3</sub>

ORAL

Abstract

CrI3 is a rare example of a material supporting intrinsic magnetic order at the two-dimensional limit. Here, we report on the non-equilibrium lattice and spin dynamics in CrI3 across the magnetic phase transition. Our experiments reveal multi-step optically induced demagnetization dynamics that are driven by Elliott-Yafet spin-flip scattering due to spin-orbit coupling in the manifold of valence band states. In addition, we observe pronounced coherent oscillations in the time-resolved polarization rotation signal under off-resonant excitation, which are commensurate with phonon modes of A1g symmetry. Intriguingly, the amplitude of the c-axis A1g mode shows a strong pump helicity dependence below the Curie temperature. This correlation between magnetic order and vibrational amplitude suggests a strong coupling between the spin and lattice degrees of freedom. This, in turn, allows structural distortions to modulate magnetic exchange coupling, ultimately yielding spin-coupled phonon modes as confirmed by our density functional theory and dynamical simulations of the coupled spin-phonon system. Our work highlights the potential for coherent optical control of low-dimensional magnetism, with profound implications for future nanoscale magneto-optical devices.

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Presenters

  • Prashant Padmanabhan

    • Los Alamos National Laboratory
    • Center for Integrated Nanotechnologies, Los Alamos National Laboratory

Authors

  • Prashant Padmanabhan

    • Los Alamos National Laboratory
    • Center for Integrated Nanotechnologies, Los Alamos National Laboratory

  • Finn Lasse Buessen

    • Univ of Toronto
    • Department of Physics, University of Toronto

  • Roxanne Tutchton

    • Los Alamos National Laboratory
    • Center for Integrated Nanotechnologies, Los Alamos National Laboratory

  • Kevin WC Kwock

    • Columbia Univ
    • The Fu Foundation School of Engineering and Applied Science, Columbia University

  • Samuel Gilinsky

    • Center for Integrated Nanotechnologies, Los Alamos National Laboratory

  • Min-Cheol Lee

    • Los Alamos National Laboratory
    • Center for Integrated Nanotechnologies, Los Alamos National Laboratory

  • Michael A McGuire

    • Materials Science and Technology Division, Oak Ridge National Laboratory
    • Oak Ridge National Lab
    • Oak Ridge National Laboratory

  • Srinivasa Singamaneni

    • Department of Physics, The University of Texas at El Paso

  • Dmitry Yarotski

    • Los Alamos National Laboratory
    • CINT, Los Alamos National Lab
    • Department of Physics, Massachusetts Institute of Technology
    • Center for Integrated Nanotechnologies, Los Alamos National Laboratory

  • Arun Paramekanti

    • Physics, Univ of Toronto
    • Univ of Toronto
    • Department of Physics, University of Toronto

  • Jian-Xin Zhu

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

  • Rohit P Prasankumar

    • Los Alamos National Laboratory
    • CINT, Los Alamos National Lab
    • Center for Integrated Nanotechnologies, Los Alamos National Laboratory