  Inducing and controlling electrostatic barriers in two-dimensional (2D)
quantum materials has shown extraordinary promise to enable control of charge
carriers, and is key for the realization of nanoscale electronic and
optoelectronic devices1-10. Because of their atomically thin nature, the 2D
materials have a congenital advantage to construct the thinnest possible p-n
junctions1,3,7,9,10. To realize the ultimate functional unit for future
nanoscale devices, creating atomically wide electrostatic barriers embedded in
2D materials is desired and remains an extremely challenge. Here we report the
creation and manipulation of atomically wide electrostatic barriers embedded in
graphene WSe2 heterostructures. By using a STM tip, we demonstrate the ability
to generate a one-dimensional (1D) atomically wide boundary between 1T-WSe2
domains and continuously tune positions of the boundary because of
ferroelasticity of the 1T-WSe2. Our experiment indicates that the 1D boundary
introduces atomically wide electrostatic barriers in graphene above it. Then
the 1D electrostatic barrier changes a single graphene WSe2 heterostructure
quantum dot from a relativistic artificial atom to a relativistic artificial
molecule.
