Physics Colloquium with Shaffique Adam on Strong Correlations in Twisted Materials

Shaffique Adam (Hosted by Henriksen) from Yale NUS College will be presenting the colloquium "Strong Correlations in Twisted Materials"

Moiré patterns are well known in the visual arts and textile industries -- the term comes from the textured patterns seen in mohair silk fabrics.  It arises whenever two periodic structures are superimposed giving new periodicities.  Remarkably, applying these ideas to atomically thin materials, the coupling between the layers enables designer materials where material properties like bandwidth, electron velocity, and band topology can be controllably altered.  With more than 1,000 possible “easily exfoliatable” materials to play with, this opens up the possibility of making billions of designer band structures with promising applications to both fundamental science and technology.


In this colloquium, I will first discuss the remarkable progress in this area.  In less than 15 years since the first isolation of two-dimensional materials, our experimental colleagues are now able to tune the twist angle between adjacent atomic monolayers to within 0.1 degrees.  This enables, for example, changing the electronic bandwidth by a factor of 1000, or the strength of correlations by a factor of 100.  In the second part of this talk, I will pick up on this idea of strong correlations in a two-dimensional topological band-structure, and discuss the effect of Coulomb interactions on the Fermi surface shape.