Physics Colloquium

Continuous Mott Transition in Moiré Heterostructures

Debanjan Chowdhary
Assistant Professor
Department of Physics
Cornell University, Ithaca, NY

How a metal--an electrical conductor--transitions continuously into an electrical insulator with increasing strength of electronic interactions is an old puzzle in condensed matter physics. Moiré materials provide a new platform to revisit these questions from a fresh perspective. Recent experiments in moiré heterostructures studying such metal-insulator transitions have already revealed several fascinating connections to unconventional quantum criticality beyond the Landau-Ginzburg-Wilson paradigm. Inspired by these and related experiments, I will discuss some new theoretical developments in describing a class of continuous quantum phase transitions between metals with generic electronic Fermi surfaces and interaction-induced Mott insulators.

Bio
Our group works on a variety of problems in theoretical condensed matter Physics. The concept of quasiparticles, the long-lived excitations above the ground state of a many-body system, which remain particle-like even in the presence of strong electron-electron interactions, has been immensely successful in describing the phenomenology of electronic systems. However, recent decades have seen an increasing number of challenges to these ideas, following the discovery of phenomena such as the fractional quantum Hall effect, ‘strange’ metals and frustrated quantum magnetism. A central theme of our research is the Physics of such strongly correlated quantum systems, where the effects of interaction can lead to the emergence of dramatic new collective phenomena, not describable in terms of the standard quasiparticle-based framework. Many of these problems are inspired by our quest for understanding experiments on a variety of exotic materials, such as unconventional superconductors, quantum spin liquids and non-Fermi liquids,  from a fundamental microscopic point of view.