  In van der Waals heterostructures, electronic bands of two-dimensional (2D)
materials, their nontrivial topology, and electron-electron interactions can be
dramatically changed by a moire pattern induced by twist angles between
different layers. Such process is referred to as twistronics, where the tuning
of twist angle can be realized through mechanical manipulation of 2D materials.
Here we demonstrate an experimental technique that can achieve in situ
dynamical rotation and manipulation of 2D materials in van der Waals
heterostructures. Using this technique we fabricated heterostructures where
graphene is perfectly aligned with both top and bottom encapsulating layers of
hexagonal boron nitride. Our technique enables twisted 2D material systems in
one single stack with dynamically tunable optical, mechanical, and electronic
properties.
