Moiré is Different: Wigner Solidification at Magic Angles in Doped Twisted bi-layer Graphene

Dr. Philip Phillips (host Nussinov), UIUC
October 3, 2018 at 4:00 pm
204 Crow
Event Description 

In a recent paper, the MIT group led by Pablo Jarillo-Herrero has found that doping twisted bi-layer graphene can generate strongly correlated insulating states superconductivity at particular twist angles called magic angles. This problem has excited the condensed matter community because it establishes that graphene, normally viewed as a weakly interacting system, is a new platform for strongly correlated physics. The experimentalists as well as a host of theorists have attributed the insulating states to Mottness. However, this interpretation has been called into question because the simplest experimental set-up in which one charge resides in each unit cell exhibits metallic transport not Mott insulation. I will review the experiments and 1) explain why the one-electron/unit cell case is a metal, 2) show that the insulating behaviour is consistent with a series of Wigner crystalline states, and 3) discuss how superconductivity arises from doping such crystalline st ates.

Coffee: 2:45 pm, 241 Compton