Observation of topologically protected states at crystalline phase boundaries in single-layer WSe2
Transition metal dichalcogenide materials are unique in the wide variety of structural and electronic phases they exhibit in the two-dimensional limit. Here we show how such polymorphic flexibility can be used to achieve topological states at highly ordered phase boundaries in a new quantum spin Hall insulator (QSHI), 1T'-WSe2. We observe edge states at the crystallographically aligned interface between a quantum spin Hall insulating domain of 1T'-WSe2 and a semiconducting domain of 1H-WSe2 in contiguous single layers. The QSHI nature of single-layer 1T'-WSe2 is verified using angle-resolved photoemission spectroscopy to determine band inversion around a 120 meV energy gap, as well as scanning tunneling spectroscopy to directly image edge-state formation. Using this edge-state geometry we confirm the predicted penetration depth of one-dimensional interface states into the two-dimensional bulk of a QSHI for a well-specified crystallographic direction. In conclusion, these interfaces create opportunities for testing predictions of the microscopic behavior of topologically protected boundary states.
- Research Organization:
- SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States); Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)
- Sponsoring Organization:
- USDOE
- Grant/Contract Number:
- AC02-05CH11231; AC02-76SF00515; MAT2017-88377-C2-1-R; 306504; EFMA-1542741
- OSTI ID:
- 1465222
- Alternate ID(s):
- OSTI ID: 1475489; OSTI ID: 1477419
- Journal Information:
- Nature Communications, Journal Name: Nature Communications Vol. 9 Journal Issue: 1; ISSN 2041-1723
- Publisher:
- Nature Publishing GroupCopyright Statement
- Country of Publication:
- United Kingdom
- Language:
- English
Web of Science
Similar Records
Bending effects and optical properties of WSe2 nanoribbons of topological phase
Proximity-induced superconducting gap in the quantum spin Hall edge state of monolayer WTe2