Speaker: Dr. Daniel Massatt rom the University of Chicago (invited by Helen Li)
Date and Time: Friday, March 18, 2022, 11:00-12:00 in person. The talk will also be broadcast online via Zoom for those unable to attend in person. Please contact Will Brian to obtain the Zoom link.
Title: Electronic Structure of Incommensurate 2D Heterostructures with Mechanical Relaxation
Since their discovery by Geim, 2D heterostructures have become a hotbed of research due to their novel structure. Stacking various materials on top of each other allows for a vast range of possible materials and corresponding properties. However, this stacking typically leads to an aperiodic, or incommensurate, structure due to lattice mismatch or rotational misalignment. This incommensuration increases the potential for tunability of electronic and mechanical properties, leading for example to the famous discovery of unconventional superconductivity of twisted bilayer graphene at the magic angle.
Experiments are vastly more expensive than numerical simulations, so much work is needed on building analysis and algorithms for understanding and computing efficiently for appropriate models. In this work, we discuss configuration and momentum space methodologies to build algorithms to compute observables of incommensurate heterostructures with mechanical relaxation in a tight-binding framework. We exploit the ergodicity of the misalignment, and for appropriate materials (such as those with conic or parabolic bands) we use carefully selected perturbative expansions in momentum space.