Structure-driven topological phase transition in a quasi-one-dimensional ferromagnetic Weyl semi-metal

ORAL

Abstract

The quasi-one-dimensional compound K2Cr8O16 is famous for exhibiting a structure-driven ferromagnetic-metal-to-ferromagnetic-insulator transition (FM-MIT), a transition not explained by the Hubbard model. Since the doped metallic phase of K2Cr8O16 belongs to the special class of magnetic Weyl semimetals, this FM-MIT is also a topological phase transition. In this work, we show that the unique topological phase transition from a trivial insulator to a topological magnetic Weyl semimetals is structure driven, and can be achieved using temperature as the tuning parameter. Through inelastic X-ray and neutron scattering experiments combined with first-principles theoretical calculations, we demonstrate the absence of divergences in the electronic and magnetic responses across the transition, disproving the previous proposition that this transition is driven by a Peierls instability. We further establish that the exchange interaction is mainly superexchange in nature, which persists across the transition, as opposed to double-exchange type as previously proposed. This work represents the first systematic study of a topological phase transition for a structure driven ferromagnetic Weyl semimetal, paving way for novel topological spintronics devices.

*This research was supported by the Swedish Research Council (VR) via a Neutron Project Grant (Dnr. 2016-06955), the Carl Tryggers Foundation for Scientific Research (CTS-18:272), and the Swedish Foundation for Strategic Research (SSF) within the Swedish national graduate school in neutron scattering (SwedNess). Y.S. is funded by VR through a Starting Grant (Dnr. 2017-05078) as well as the Chalmers Area of Advance-Materials Science. J.S. acknowledges support from Japan Society for the Promotion Science (JSPS) KAKENHI Grants No. JP18H01863 and No. JP20K21149. O.E. and C.S.O. acknowledge support from the Swedish Research Council (VR), the Knut and Alice Wallenberg Foundation, the Swedish Foundation for Strategic Research (SSF), the Swedish Energy Agency (Energimyndigheten), ERC (synergy grant FASTCORR, project 854843), eSSENCE, and STandUPP. We also would like to acknowledge the Swedish National Infrastructure for Computing (SNIC) for computational support.

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Presenters

  • Chin Shen Ong

    • University of California at Berkeley, and Lawrence Berkeley National Laboratory
    • Uppsala University

Authors

  • Chin Shen Ong

    • University of California at Berkeley, and Lawrence Berkeley National Laboratory
    • Uppsala University

  • Ola K Forslund

    • KTH Royal Institute of Technology

  • Nicolas Gauthier

    • Université de Sherbrooke, Canada
    • SLAC National Accelerator Laboratory and Stanford University

  • Hiroshi Uchiyama

    • SPring-8/JASRI

  • Daniel Mazzone

    • Paul Scherrer Institute

  • Masafumi Horio

    • SPring-8/JASRI

  • Nami Matsubara

    • KTH Royal Institute of Technology

  • Elisabetta Nocerino

    • KTH Royal Institute of Technology

  • Deepak J Mukkattukavil

    • Uppsala University

  • Konstantinos Papadopoulos

    • Chalmers University of Technology

  • Kazuya Kamazawa

    • CROSS Neutron Science and Technology Center

  • Kazuhiko Ikeuchi

    • CROSS Neutron Science and Technology Center

  • Romain Sibille

    • Paul Scherrer Institut
    • Paul Scherrer Institute

  • Antonio M dos Santos

    • Oak Ridge National Lab

  • Hidenori Takagi

    • Max Planck Institute for Solid State Physics

  • Masahiko Isobe

    • Max Planck Institute for Solid State Research
    • Max-Planck-Institute for Solid State Research

  • Jun Sugiyama

    • CROSS Neutron Science and Technology Center

  • Johan Chang

    • University of Zürich
    • Department of Physics, University of Zürich, Winterthurerstrasse 190, Zurich, Switzerland
    • University of Zurich

  • Yasmine Sassa

    • Chalmers University of Technology

  • Olle Eriksson

    • Uppsala University
    • Uppsala University, Sweden, Örebro University, Sweden

  • Martin Mansson

    • KTH Royal Institute of Technology