Phenomenological Theory of twisted bilayer graphene

QUEST Center event
No
Speaker
Yuval Oreg -The Weizmann Institute of Science
Date
27/04/2023 - 13:30 - 12:30Add to Calendar 2023-04-27 12:30:00 2023-04-27 13:30:00 Phenomenological Theory of twisted bilayer graphene Twisted bilayer graphene systems have emerged as a new platform for intriguing many-body states of matter. The application of an external electric field drives the system from an insulating state to a topological state that does not conduct in bulk but does conduct on the sample edges and even to superconducting states. I will introduce and analyze a model that sheds light on the interplay between correlated insulating states, superconductivity, and flavor-symmetry breaking in magic-angle twisted bilayer graphene. Using a variational mean-field theory, we determine the normal-state phase diagram of our model as a function of the band filling. Our model elucidates how the intricate form of the interactions and the particle-hole asymmetry of the electronic spectrum determine the phase diagram. It also explains how subtle differences between devices may lead to experimentally observing different behaviors. A similar model with minor modifications is suitable for describing other systems, such as untwisted and twisted trilayer Graphene and transition metal dichalcogenides structures. Conference room on the 0th floor of Resnick building Department of Physics physics.dept@mail.biu.ac.il Asia/Jerusalem public
Place
Conference room on the 0th floor of Resnick building
Abstract

Twisted bilayer graphene systems have emerged as a new platform for intriguing many-body states of matter. The application of an external electric field drives the system from an insulating state to a topological state that does not conduct in bulk but does conduct on the sample edges and even to superconducting states. I will introduce and analyze a model that sheds light on the interplay between correlated insulating states, superconductivity, and flavor-symmetry breaking in magic-angle twisted bilayer graphene. Using a variational mean-field theory, we determine the normal-state phase diagram of our model as a function of the band filling. Our model elucidates how the intricate form of the interactions and the particle-hole asymmetry of the electronic spectrum determine the phase diagram. It also explains how subtle differences between devices may lead to experimentally observing different behaviors. A similar model with minor modifications is suitable for describing other systems, such as untwisted and twisted trilayer Graphene and transition metal dichalcogenides structures.

Last Updated Date : 23/04/2023