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Monday, August 11 • 14:00 - 16:00
Quantum Hall Effects II

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14:00-14:30
Invited: Jurgen Smet
Unconventional Even Denominator Fractional Quantum Hall Physics in ZnO Two-Dimensional Electron Systems

Until recently the study of even denominator fractional quantum Hall states (FQH) was the exclusive privilege of the III-V semiconductor community. In particular, the observation of FQH-states in the second Landau level at filling 5/2 and 7/2 in GaAs based 2D electron systems has unleashed a flood of theoretical as well as experimental effort due to their exotic properties. These ground states are in essence thought to be p-wave superconductors with zero energy Majorana modes as excitations. Here we report the observation of such physics outside of the realm of III-V heterostructures in the emergent ZnO 2D electron system. It not only exhibits a robust FQH-state at filling 7/2, but also at unconventional fillings. There is for instance an incipient 9/2 state in perpendicular field and a fully resolved 3/2 FQH-state emerges when tilting the sample. The latter is believed to also be a genuine single component incompressible ground state of paired composite fermions analogous to the 5/2 state in GaAs. Even though the ZnO quality can still not compete with GaAs, the use of ZnO for investigating even denominator FQH physics offers a powerful additional degree of freedom. Because the Zeeman splitting and the cyclotron energy are comparable, it is possible at a fixed filling to alter the orbital character of the partially filled level at the Fermi energy by tilting the sample. The orbital character of this uppermost level plays a crucial role for the development and stability of even denominator as well as other FQH-states. 

Co-authors: Joe Falson, Denis Maryenko, Benedikt Friess, Ding Zhang, Yusuke Kozuka, Atsushi Tsukazaki, Masashi Kawasaki

14:30-14:45
Oral: Xiao Li
Nematic Valley Ordering in SnTe in the Quantum Hall Regime
Co-authors: Fan Zhang, Qian Niu, Allan MacDonald

14:45-15:00
Oral: B. A. Piot

Resistive NMR in the Vicinity of the ν = 1 Quantum Hall State: Coexistence of Partially Polarized & Un-Polarized Electron Subsystems
Co-authors: W. Desrat, S. Kramer, D. K. Maude, Z. R. Wasilewski, M. Henini, R. Airey

15:00-15:15
Oral: Trevor David Rhone

Direct Probing of Local Density Fluctuations in Disordered Quantum Hall Systems Using NMR
Co-authors: Koji Muraki

15:15-15:30
Oral: Rebeca Ribeiro

Unusual Backscattering Between Quantum Hall Edge States in CVD Graphene
Co-authors: Zheng Han, Alessandro Cresti, Aron Cummings, Stephan Roche, Vincent Bouchiat, Sebastien Ducourtieux, Felicien Schopfer, Wilfrid Poirier

15:30-15:45
Oral: Shota Shirai

Filling Factor Dependence of AC-Electric-Field-Induced Nuclear Spin Resonance
Co-authors: Toru Tomimatsu, Katsushi Hashimoto, Ken Sato, Katsumi Nagase, Yoshiro Hirayama

15:45-16:00
Open 

Session Chairs
MH

Mohammad Hafezi

Assistant Professor, University of Maryland Fellow, Joint Quantum Institute, University of Maryland
Mohammad Hafezi received his diplome d'ingenieur from Ecole Polytechnique (Paris) in 2003 and his Ph.D. from Physics Department at Harvard University in 2009. He moved to the Joint Quantum Institute (NIST/University of Maryland) as a research associate and since 2012 he is a research faculty. His research is at the interface of theoretical quantum optics and condensed matter physics with a focus on fundamental physics and applications in... Read More →

Speakers
JS

Jurgen Smet

Max Planck Institute for Solid State Research
Jurgen Smet is heading the independent research group Solid State Nanophysics at the Max Planck Institute for Solid State Research. He graduated with a Master degree in Electrical Engineering from the Catholic University of Leuven in 1990. In 1994, he received his Ph. D. in Electrical Engineering and Computer Science from the Massachussets Institute of Technology, Cambridge U.S.A, with research on intrawell and interwell intersubband... Read More →


Monday August 11, 2014 14:00 - 16:00
Room 16A

Attendees (6)