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VERSION:2.0
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PRODID:UW-Madison-Physics-Events
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SEQUENCE:0
UID:UW-Physics-Event-5301
DTSTART:20200123T160000Z
DURATION:PT1H0M0S
DTSTAMP:20260415T040911Z
LAST-MODIFIED:20200121T015205Z
LOCATION:5310 Chamberlin
SUMMARY:Tunable Excitonic Ground States in Double Layer Graphene\, R. 
 G. Herb Condensed Matter Seminar\,  Yihang Zeng\, Columbia University
DESCRIPTION:Two-component quantum Hall systems\, such as double layer 
 graphene (DLG) separated by a tunnel barrier\, have been demonstrated 
 to host ground states of indirect interlayer exciton when the lowest L
 andau level (LL) in each layer is half filled. Upon decreasing the tem
 perature\, the system will condense into a macroscopically ordered sta
 te with quasi long-range phase coherence\, termed exciton condensate\,
  a superfluid of exciton. We realized the crossover between exciton co
 ndensate with strong coupling and weak coupling by changing the excito
 n density. Upon unbalancing the density in each layer\, we observe a s
 harp transition from an exciton superfluid to an exciton insulator\, i
 nsulating in both charge transport and exciton transport measurement\,
  which is interpreted as a Wigner crystal of exciton pinned by disorde
 r. With tunable Bohr radius and exciton-exciton distance\, we for the 
 first time show the entire phase diagram of the excitonic ground state
 s in the lowest LL in DLG.
URL:https://www.physics.wisc.edu/events/?id=5301
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