Large anomalous Hall effect in topological insulators with a proximitized ferromagnetic insulator

ORAL

Abstract

Ferromagnetism in topological insulators could lead to exotic quantum phenomena such as quantum anomalous Hall effect. A predominant requirement for such phenomena is the formation of an exchange gap at the Dirac surface states, being realized not only by magnetic doping but also by proximitizing ferromagnetic insulators. Here, we report on the effective gap formation driven by proximity coupling via detection of large anomalous Hall conductivity in heterostructures consisting of ferromagnetic insulator Cr2Ge2Te6 and topological insulator (Bi,Sb)2Te3. While no discernible magnetization in the (Bi,Sb)2Te3 layer is probed by spin-polarized neutron reflectometry, the emergence of large anomalous Hall effect implies that the wavefunction of the Dirac surface state gains an exchange field by penetrating into the Cr2Ge2Te6 by approximately 2-3 nm, finally activating a large Berry curvature. The presently verified mechanism of strong ferromagnetic proximity effect paves a way to enrich the proximity coupling phenomena in versatile topological quantum materials.

*This research was supported by JST CREST (no. JPMJCR16F1) and JSPS through a
research fellowship for young scientists (no. 17J03179).

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Presenters

  • Masataka Mogi

    • Applied Physics, University of Tokyo

Authors

  • Masataka Mogi

    • Applied Physics, University of Tokyo

  • Taro Nakajima

    • RIKEN Center for Emergent Matter Science
    • RIKEN CEMS
    • Center for Emergent Matter Science (CEMS), RIKEN

  • Victor Ukleev

    • PSI

  • Atsushi Tsukazaki

    • Tohoku University
    • Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
    • IMR Tohoku University
    • IMR, Tohoku Univ.
    • Institute for Materials Research, Tohoku University

  • Ryutaro Yoshimi

    • RIKEN CEMS
    • CEMS, RIKEN
    • Center for Emergent Matter Science, RIKEN

  • Minoru Kawamura

    • RIKEN CEMS
    • CEMS, RIKEN

  • Kei Takahashi

    • RIKEN CEMS
    • CEMS, RIKEN
    • Center for Emergent Matter Science, RIKEN

  • Takayasu Hanashima

    • CROSS

  • Kazuhisa Kakurai

    • CROSS
    • Comprehensive Research Organization for Science and Society (CROSS)
    • Neutron Science and Technology Center, Comprehensive Research Organization for Science and Society

  • Taka-hisa Arima

    • GSFS, University of Tokyo
    • University of Tokyo
    • Graduate School of Frontier Sciences, The University of Tokyo

  • Masashi Kawasaki

    • The University of Tokyo
    • Department of Applied Physics and Quantum-Phase Electronics Center (QPEC), The University of Tokyo, Tokyo 113-8656, Japan
    • University of Tokyo
    • Applied Physics and QPEC, University of Tokyo
    • Department of applied physics, The University of Tokyo
    • Department of Applied Physics and Quantum-Phase Electronics Center (QPEC), the University of Tokyo
    • Department of Applied Physics and Quantum-Phase Electronics Center (QPEC), Univ. of Tokyo, Tokyo, Japan.

  • Yoshinori Tokura

    • RIKEN Center for Emergent Matter Science (CEMS)
    • RIKEN Center for Emergent Matter Science
    • RIKEN CEMS
    • RIKEN Center for Emergent Matter Science (CEMS), Wako, Japan
    • Center for Emergent Matter Science (CEMS), RIKEN
    • Department of Applied Physics and Quantum-Phase Electronics Center, University of Tokyo
    • University of Tokyo
    • University of Tokyo and RIKEN CEMS
    • CEMS, RIKEN
    • Center for Emergent Matter Science, RIKEN
    • Department of Applied Physics, University of Tokyo
    • University of Tokyo and RIKEN-CEMS