Visualizing Quantum Anomalous Hall States at the atomic scale with STM Landau Level Spectroscopy

ORAL

Abstract

The quantum anomalous Hall (QAH) effect appears in ferromagnetic topological insulators (FMTIs) when a Dirac mass gap opens in the spectrum of the topological surface states (SSs). Although the mean mass gap can exceed 28 meV (∼320 K), the QAH effect is frequently only detectable at temperatures below 1 K. Using Landau level spectroscopic imaging, we compare the electronic structure of FMTI Cr0.08(Bi0.1Sb0.9)1.92Te3 to that of its nonmagnetic parent (Bi0.1Sb0.9)2Te3 to find electrostatic and magnetic disorders conspire to drastically suppress the minimum mass gap to below 100 μeV for nanoscale regions separated by <1 μm. This fundamentally limits QAH in Sb2Te3-based FMTI materials to very low temperatures.

*Y.X.C., A.K., R.S., G.G., and K.F. acknowledge support from the US Department of Energy, Office of Basic Energy Sciences, under contract number DEAC02-98CH10886. X.L. acknowledges support from the Kavli Institute at Cornell through the KIC Postdoctoral Fellowship and from the Keck Foundation. J.C.S.D. and P.O.S. acknowledge support from the Gordon and Betty Moore Foundation’s EPiQS Initiative through Grant GBMF4544. J.C.S.D. acknowledges support from Science Foundation Ireland under Award SFI 17/RP/5445 and from the European Research Council (ERC) under Award DLV-788932.

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Presenters

  • Yi Xue Chong

    • Cornell University
    • Physics, Cornell University

Authors

  • Yi Xue Chong

    • Cornell University
    • Physics, Cornell University

  • Xiaolong Liu

    • Cornell University
    • Physics, Cornell University

  • Rahul Sharma

    • Cornell University
    • Quantum Materials Center, University of Maryland; Laboratory of Atomic and Solid States Physics, Cornell University
    • University of Maryland, College Park

  • Andrey Kostin

    • Cornell University
    • Laboratory of Atomic and Solid State Physics, Cornell University

  • Genda Gu

    • Brookhaven National Laboratory
    • Brookhaven National Laboratories
    • Brookhaven national lab
    • Brookhaven National Labs
    • Condensed Matter Physics and Materials Science Department
    • Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory
    • CMPMS, Brookhaven National Laboratory
    • Brookhaven National Lab
    • COndensed Matter Physics and Materials Science Department, Brookhaven National Laboratory

  • Kazuhiro Fujita

    • CMPMS, Brookhaven National Laboratory
    • Brookhaven National Laboratory

  • James C Davis

    • Cornell University
    • Department of Physics, University of Oxford
    • University College Cork
    • Laboratory of Atomic and Solid State Physics, Cornell University; Department of Physics, University College Cork; Max-Planck Institute for Chemical Physics of Solids; Clarend

  • Peter Oliver Sprau

    • University of California, San Diego
    • Advanced Development Center, ASML
    • Advanced Development Center, ASML; Laboratory of Atomic and Solid State Physics, Cornell University