Topological Kondo insulator nanowire as a probe tip for spin-sensitive imaging

ORAL

Abstract

Spin-momentum locking in topological surface states (TSS) gives rise to exotic spin-dependent phenomenon in materials like the quantum spin Hall effect, Edelstein effect, etc. Achieving these in experiments have been challenging with garden-variety topological insulators due to the coexistence of highly conducting bulk states and the TSS being buried deep in the bulk bands. However, topological Kondo insulators (TKI) are pertinent for such studies as the TSS are well isolated from the bulk by the Kondo hybridization gap and are usually pinned at the Fermi energy. Nanomaterials of topological insulators furnish enhanced surface properties and allow versatility in spintronics applications. Here, we report the fabrication and use of nanowires of a TKI as probe tips for scanning tunneling microscopy and spectroscopy (STM/S). We exploit the presence of spin-momentum locked TSS at the Fermi energy in this TKI to achieve spin-resolved tunneling. We demonstrate that the direction of spin-polarization is tied to the tunneling direction, a unique feature of TSS-dominated tunneling where the group velocity is locked to the spin direction. Our findings initiate a novel form of STM-based spectroscopy for probing spin degrees of freedom in quantum materials using topological phenomena.

*V.M acknowledges the National Science foundation for support of STM studies through DMR-2003784, and partial support from the Gordon and Betty Moore foundation EPiQS grant #9465. V.M would also like to acknowledge the Materials Research Laboratory Central Research Facilities at the University of Illinois for use of the cleanroom. X.L and F.L. are very thankful for the support of the National Science Foundation of China (Grant Nos. 51872337), National Project for the Development of Key Scientific Apparatus of China (2013YQ12034506). X.W. acknowledges financial support from National MagLab, which is funded by the National Science Foundation (DMR-1644779) and the state of Florida.

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Publication: Manuscript in review

Presenters

  • Anuva Aishwarya

    • Department of Physics and Frederick Seitz Materials Research Laboratory, University of Illinois Urbana-Champaign, Urbana, Illinois 61801, USA
    • University of Illinois at Urbana-Champaign

Authors

  • Anuva Aishwarya

    • Department of Physics and Frederick Seitz Materials Research Laboratory, University of Illinois Urbana-Champaign, Urbana, Illinois 61801, USA
    • University of Illinois at Urbana-Champaign

  • Zhuozhen Cai

    • Department of Physics and Frederick Seitz Materials Research Laboratory, University of Illinois Urbana-Champaign, Urbana, Illinois 61801, USA

  • Arjun Raghavan

    • University of Illinois at Urbana-Champaign
    • Department of Physics and Frederick Seitz Materials Research Laboratory, University of Illinois Urbana-Champaign, Urbana, Illinois 61801, USA

  • Marisa L Romanelli

    • Department of Physics and Frederick Seitz Materials Research Laboratory, University of Illinois Urbana-Champaign, Urbana, Illinois 61801, USA

  • Xiaoyu Wang

    • National High Magnetic Field Lab,1800 E Paul Dirac Dr. Tallahassee, FL 32310

  • Xu Li

    • State Key Laboratory of Optoelectronic Materials and Technologies, Sun Yat-sen University, Guangzhou 510275, China

  • Genda Gu

    • Brookhaven National Laboratory
    • Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, NY 11973, USA

  • Taylor L Hughes

    • University of Illinois at Urbana-Champaign
    • Department of Physics and Frederick Seitz Materials Research Laboratory, University of Illinois Urbana-Champaign, Urbana, Illinois 61801, USA

  • Fei Liu

    • State Key Laboratory of Optoelectronic Materials and Technologies, Sun Yat-sen University, Guangzhou 510275, China

  • Lin Jiao

    • National High Magnetic Field Laboratory
    • National High Magnetic Field Lab 1800 E Paul Dirac Dr. Tallahassee, FL 32310

  • Vidya Madhavan

    • University of Illinois at Urbana-Champaign
    • Department of Physics and Frederick Seitz Materials Research Laboratory, University of Illinois Urbana-Champaign, Urbana, Illinois 61801, USA