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

Event Date:
2018-11-29T14:00:00
2018-11-12T15:00:00
Event Location:
AMPL 311
Speaker:
Prof. Philip W. Phillips from the University of Illinois
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Event Information:

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,

2) show that the insulating behaviour is consistent with a series of Wigner crystalline states that are enhanced by hydrostatic pressure as observed in the newest experiments of Dean and Young, and

3) discuss how superconductivity arises from doping  such crystalline states.  

Add to Calendar 2018-11-29T14:00:00 2018-11-12T15:00:00 Moiré is Different: Wigner Solidification at Magic Angles in Doped Twisted bi-layer Graphene Event Information: 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, 2) show that the insulating behaviour is consistent with a series of Wigner crystalline states that are enhanced by hydrostatic pressure as observed in the newest experiments of Dean and Young, and 3) discuss how superconductivity arises from doping  such crystalline states.   Event Location: AMPL 311