GRADUATE SEMINAR 1 (2026)

Twistronics: effects of atomic relaxation on the electronic properties of twisted multi-layer systems

SpeakerProfessor Efthimios Kaxiras, Harvard University, USA
Date/TimeMonday, 2 Feb, 12pm
LocationS11-02-07 Conference room
ModeratorAsst/Prof Li Xinwei

Abstract

The field of “twistronics” was born with the experimental discovery of correlated electron behavior and super-conductivity in twisted bilayer graphene. Since then, a great number of new systems have been observed, consisting of two or more twisted layers and exhibiting a wide range of interesting electronic behavior. In this seminar we will concentrte on the effect of atomic relaxations in these systems, and its importance in determining the electronic behavior at the single-partilce level. We will explore both the theoretical concepts and the underlying symmetries involved in determining accurate atomic relaxations for a range of systems of interest. We will also emphasize the importance of this relaxation in understanding the electronic states that emerge.

Generalized stacking fault energy surfaces (left column) for graphene (top row) and molybdenum disulfide (bottom row), and the corresponding atomic relaxation patterns (right column).

Biography

Efthimios Kaxiras received his PhD in theoretical condensed matter physics from MIT. He is presently the John Hasbrouck Van Vleck Professor of Pure and Applied Physics at Harvard University. He has been a Visiting Faculty at ETH-Zurich, EPF-Lausanne, the University of Ioannina and the University of Crete. He has served as Director of Harvard’s Institute for Applied Computational Science and the Initiative in Innovative Computing. He holds several distinctions such as Fellow of the American Physical Society and Chartered Physicist and Fellow of the Institute of Physics (London).

He has published widely in the area of computational materials science with emphasis on multiscale simulations of complex physical phenomena. He has also written two textbooks on the physics of solids. His recent research focuses on the extraordinary properties of two-dimensional, layered materials and in particular on the topic of twistronics (a term introduced by his research group).