Bulletin of the American Physical Society
APS March Meeting 2021
Volume 66, Number 1
Monday–Friday, March 15–19, 2021; Virtual; Time Zone: Central Daylight Time, USA
Session E50: Unconventional States and Excitations in the Fractional Quantum Hall Effect
8:00 AM–11:00 AM,
Tuesday, March 16, 2021
Sponsoring Unit: DCMP
Chair: Mitali Banerjee, Columbia University
Abstract: E50.00005 : Precursors to Exciton Condensation in Quantum Hall Bilayers*
10:24 AM–11:00 AM
The nature of the transition between the incoherent phase at large layer separation and the coherent excitonic phase at small separations remains poorly understood. In this talk I will report on recent experiments which shed new light on the transition. In particular, I will discuss tunneling spectroscopy measurements which reveal evidence for interlayer electron-hole correlations at layer separations near, but above, the transition to the exciton condensate at total Landau level filling νT=1. These correlations are manifested by a nonlinear suppression of the Coulomb pseudogap which inhibits low energy interlayer tunneling in weakly coupled bilayers and an anomalous dependence of the pseudogap on an added in-plane magnetic field . The pseudogap suppression is strongest at νT=1 and grows rapidly as the critical layer separation for exciton condensation is approached from above. These and other observations suggest that electron-hole pairing fluctuations exist in the incoherent phase well above the critical layer separation, in a manner reminiscent of Cooper pair fluctuations above the superconducting critical temperature.
*This work was supported by the Caltech Institute for Quantum Information and Matter, an NSF Physics Frontiers Center, the Gordon and Betty Moore Foundation through Grants GBMF1250 and GBMF4420, and the NSF via MRSEC Grant No. 1420541.
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