Ferromagnetism in Cr-doped Bi<sub>2</sub>Se<sub>3</sub> thin films via surface-state engineering and carrier-selective anomalous Hall effect

ORAL

Abstract

Anomalous Hall effect (AHE) is a non-linear Hall effect appearing on magnetic conductors, boosted by internal magnetism beyond what is expected from ordinary Hall effect. With the recent discovery of quantized version of the AHE, the quantum anomalous Hall effect (QAHE), in Cr- or V-doped topological insulator (TI) (Sb,Bi)2Te3 thin films, AHE in magnetic TIs has been attracting significant interest. However, one of the puzzles in this system has been that while Cr- or V-doped (Sb,Bi)2Te3 and V-doped Bi2Se3 exhibit ferromagnetic (hysteretic) AHE, Cr-doped Bi2Se3 has failed to exhibit even ferromagnetic AHE, the necessary predecessor to QAHE, though it is the first material predicted to exhibit QAHE. Here, we have successfully implemented ferromagnetic AHE in Cr-doped Bi2Se3 thin films by utilizing a surface state engineering scheme. Surprisingly, all the observed ferromagnetic AHE, as in other Cr- or V-doped TIs, are always p-type even if the majority carrier type remains n-type. This can be well explained by a carrier-selective anomalous-Hall-effect model in which the local magnetic moments interact only through p-type carriers.

*This work is supported by Gordon and Betty Moore Foundation’s EPiQS Initiative (GBMF4418) and National Science Foundation (NSF) (EFMA-1542798).

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Presenters

  • Jisoo Moon

    • Rutgers, the State University of New Jersey
    • Department of Physics and Astronomy, Rutgers, the State University of New Jersey
    • Physics and Astronomy, Rutgers, The State University of New Jersey
    • Rutgers University
    • Rutgers University, New Brunswick

Authors

  • Jisoo Moon

    • Rutgers, the State University of New Jersey
    • Department of Physics and Astronomy, Rutgers, the State University of New Jersey
    • Physics and Astronomy, Rutgers, The State University of New Jersey
    • Rutgers University
    • Rutgers University, New Brunswick

  • Nikesh Koirala

    • Massachusetts Institute of Technology
    • Physics and Astronomy, Rutgers, The State University of New Jersey
    • Rutgers University - New Brunswick

  • Maryam Salehi

    • Rutgers, the State University of New Jersey
    • Materials Science and Engineering, Rutgers, The State University of New Jersey
    • Materials Sci. & Eng., Rutgers University
    • Rutgers University, New Brunswick
    • Rutgers University
    • Rutgers University - New Brunswick

  • Seongshik Oh

    • Rutgers, the State University of New Jersey
    • Center for Quantum Materials Synthesis and Department of Physics and Astronomy, Rutgers, the State University of New Jersey
    • Physics and Astronomy, Rutgers, The State University of New Jersey
    • Physics, Rutgers University
    • Physics, Rutgers, The State University of New Jersey
    • Rutgers University
    • Rutgers University - New Brunswick