Manipulating Topological Domain Boundaries in the Single-Layer Quantum Spin Hall Insulator 1T'-WSe2

Zahra Pedramrazi; Charlotte Herbig; Artem Pulkin; Shujie Tang; Madeleine Phillips; Dillon Wong; Hyejin Ryu; Michele Pizzochero; Yi Chen; Feng Wang; Eugene J Mele; Zhi-Xun Shen; Sung-Kwan Mo; Oleg V Yazyev; Michael F Crommie

doi:10.1021/acs.nanolett.9b02157

Manipulating Topological Domain Boundaries in the Single-Layer Quantum Spin Hall Insulator 1T'-WSe₂

Nano Lett. 2019 Aug 14;19(8):5634-5639. doi: 10.1021/acs.nanolett.9b02157. Epub 2019 Jul 29.

Authors

Zahra Pedramrazi¹, Charlotte Herbig¹, Artem Pulkin^{2

3}, Shujie Tang^{4

5

6}, Madeleine Phillips^{7

8}, Dillon Wong¹, Hyejin Ryu^{4

9}, Michele Pizzochero², Yi Chen¹, Feng Wang^{1

10

11}, Eugene J Mele⁷, Zhi-Xun Shen^{5

6}, Sung-Kwan Mo⁴, Oleg V Yazyev^{2

12}, Michael F Crommie^{1

10

11}

Affiliations

¹ Department of Physics , University of California at Berkeley , Berkeley , California 94720 , United States.
² Institute of Physics , Ecole Polytechnique Fédérale de Lausanne (EPFL) , CH-1015 Lausanne , Switzerland.
³ Division of Chemistry and Chemical Engineering , California Institute of Technology , Pasadena , California 91125 , United States.
⁴ Advanced Light Source , Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States.
⁵ Stanford Institute for Materials and Energy Sciences , SLAC National Accelerator Laboratory , Menlo Park , California 94025 , United States.
⁶ Geballe Laboratory for Advanced Materials, Departments of Physics and Applied Physics , Stanford University , Stanford , California 94305 , United States.
⁷ Department of Physics and Astronomy , University of Pennsylvania , Philadelphia , Pennsylvania 19104 , United States.
⁸ Center for Computational Materials Science , Naval Research Laboratory , Washington , D.C. 20375 , United States.
⁹ Center for Spintronics , Korea Institute of Science and Technology , Seoul 02792 , Korea.
¹⁰ Materials Sciences Division , Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States.
¹¹ Kavli Energy NanoScience Institute at the University of California Berkeley and the Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States.
¹² National Centre for Computational Design and Discovery of Novel Materials MARVEL , Ecole Polytechnique Fédérale de Lausanne (EPFL) , CH-1015 Lausanne , Switzerland.

PMID: 31329449
DOI: 10.1021/acs.nanolett.9b02157

Abstract

We report the creation and manipulation of structural phase boundaries in the single-layer quantum spin Hall insulator 1T'-WSe₂ by means of scanning tunneling microscope tip pulses. We observe the formation of one-dimensional interfaces between topologically nontrivial 1T' domains having different rotational orientations, as well as induced interfaces between topologically nontrivial 1T' and topologically trivial 1H phases. Scanning tunneling spectroscopy measurements show that 1T'/1T' interface states are localized at domain boundaries, consistent with theoretically predicted unprotected interface modes that form dispersive bands in and around the energy gap of this quantum spin Hall insulator. We observe a qualitative difference in the experimental spectral line shape between topologically "unprotected" states at 1T'/1T' domain boundaries and protected states at 1T'/1H and 1T'/vacuum boundaries in single-layer WSe₂.

Keywords: Scanning tunneling microscopy; domain boundary; ferroelasticity; quantum spin hall insulators; transition metal dichalcogenides.