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DTSTART:20230406T210000Z
UID:171949@events.unl.edu
DTSTAMP:20230329T153754Z
ORGANIZER;CN=Physics Department:MAILTO:paoffice2@unl.edu
SUMMARY:Department of Physics & Astronomy Colloquium
STATUS:CONFIRMED
DESCRIPTION:Dr. Jun Zhu of Penn State University will present her colloquiu
m topic\, "Many-body Ground States and Collective Excitations in a Tunable
2D System" in-person. \n\nAbstract\: The Landau levels of a two-dimension
al electron system support a plethora of fascinating many-body ground stat
es and collective low-energy excitations\, thanks to enhanced electron-ele
ctron interactions and the characteristics of the LL wave functions. The n
=1 LL is particularly fascinating as it hosts even-denominator fractional
quantum Hall states and other exotic topological orders that are potential
ly useful in topological quantum computation. In this talk\, I will descri
be a few recent experiments of ours in Bernal-stacked bilayer graphene\, w
hich is a remarkably tunable platform for exploring emergent phenomena. I
will show our observations of a new even-denominator fractional quantum Ha
ll state at filling factor 5/2 and its spontaneous valley isospin polariza
tion and discuss the particle-hole symmetry breaking of a family of even-d
enominator fractional quantum Hall states in bilayer graphene. In the seco
nd half of the talk\, I will describe an experiment probing the momentum d
ispersion of gapless spin wave excitations of a quantum Hall easy-plane ca
nted-antiferromagnet using transport techniques and a Fabry-Perot resonant
cavity. This strongly correlated magnetic state forms at the charge neutr
ality point of bilayer graphene purely through Coulomb interactions and ma
y support spin superfluidity.\n\nReferences\:\n1. K. Huang\, H. Fu\, Danie
lle Reifsnyder Hickey\, Nasim Alem\, Xi Lin\, K. Watanabe\, T. Taniguchi\,
J. Zhu\, "Valley Isospin Controlled Fractional Quantum Hall States in Bil
ayer Graphene"\, Physical Review X 12\, 031019 (2022).\n2. H. Fu\, K. Huan
g\, K. Watanabe\, T. Taniguchi\, and J. Zhu\, “Gapless Spin Wave Transpo
rt through a Quantum Canted Antiferromagnet”\, Physical Review X 11\, 02
1012 (2021)
LOCATION:Jorgensen Hall Room 136
URL://events.unl.edu/cas/2023/04/06/171949/
DTEND:20230406T220000Z
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