Physics - Condensed Matter Seminar

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

Event Type
Physics - Condensed Matter
190 ESB
Sep 14, 2018   1:00 pm  
Philip Phillips, University of Illinois at Urbana-Champaign

In a recent paper, the MIT group led Pablo Jarillo-Herrero has found that doping twisted bi-layer graphene can generate strongly correlated insulating states and 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 (except under extremely high pressure), 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 states. 

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