Events at Physics |
Events on Thursday, October 24th, 2024
- R. G. Herb Condensed Matter Seminar
- In-situ twisting and imaging of moiré superlattices
- Time: 10:00 am - 6:00 pm
- Place: 5310 Chamberlin
- Speaker: Monica Allen, UCSD
- 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.
- Host: Alex Levchenko