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Title: Observation of topologically protected states at crystalline phase boundaries in single-layer WSe2

Journal Article · · Nature Communications

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
Citation Metrics:
Cited by: 85 works
Citation information provided by
Web of Science

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