General Physics Colloquium, Professor Cory Dean, Columbia University

Title:  Twist and strain control in moiré materials

Host:  Xiaomeng Liu

Abstract: Moiré superlattices in twisted 2D materials have generated tremendous excitement as a platform for achieving quantum properties on demand. Small variations in the moiré pattern can substantially alter a device’s electronic properties, providing a new paradigm in materials design and engineering.  However, the moiré pattern is highly sensitive to the interlayer atomic registry, and current assembly techniques suffer from imprecise control of the average twist angle, spatial inhomogeneity in the local twist angle, and distortions caused by random strain.  Here we discuss new approaches to measuring and manipulating the moiré patterns in heterostructures fabricated from 2D materials. We review progress towards realizing improved twist-angle homogeneity and reduced random strain in order to realize moiré patterns with precise wavelength and ultralow disorder.  The ability to precisely tune the twist angle and strain within a 2D heterostructure, in the absence of uncontrolled distortions, paves the way for moiré band structure engineering in the disorder-free limit, including the exciting possibility that moiré patterning can be used as a generalized quantum simulation platform to study strongly correlated physics and topology in quantum materials.