Abstract: Moiré superlattices, which form in twisted stacks of 2D
materials, constitute a versatile platform for the exploration of
topological and correlated phenomena. Here we present a route to
mechanically tune the twist angle of individual atomic layers with a
precision of a fraction of a degree inside a scanning probe
microscope, which enables continuous control of the electronic band
structure in-situ. In twisted bilayer graphene, we demonstrate
nanoscale control of the moiré wavelength via mechanical rotation, as
revealed using piezoresponse force microscopy. We also extend this
methodology to create twistable boron nitride devices, enabling
dynamic control of the ferroelectric domain structure. This approach
provides a route for real-time manipulation of moiré materials, which
may allow for systematic investigation of the phase diagrams at
multiple angles in a single device. Looking forward, we will also
discuss progress on the construction of a new milliKelvin microwave
impedance microscope in a dilution refrigerator, which supports
spatially-resolved detection of topological states in the GHz regime.
As an application, I will briefly discuss the imaging of edge modes in
a Chern insulator.