4 research outputs found
Quantum spin Hall edge states and interlayer coupling in twisted-bilayer WTe
The quantum spin Hall (QSH) effect, characterized by topologically protected
spin-polarized edge states, was recently demonstrated in monolayers of the
transition metal dichalcogenide (TMD) WTe. However, the robustness of this
topological protection remains largely unexplored in van der Waals
heterostructures containing one or more layers of a QSH insulator. In this
work, we use scanning tunneling microscopy and spectroscopy (STM/STS) to
explore the topological nature of twisted bilayer (tBL) WTe which is
produce from folded monolayers, as well as, tear-and-stack fabrication. At the
tBL bilayer edge, we observe the characteristic spectroscopic signature of the
QSH edge state that is absent in topologically trivial as-grown bilayer. For
small twist angles, a rectangular moir\'e pattern develops, which results in
local modifications of the band structure. Using first principles calculations,
we quantify the interactions in tBL WTe and its topological edge states as
function of interlayer distance and conclude that it is possible to tune the
topology of WTe bilayers via the twist angle as well as interlayer
interactions