Surface Acoustic Wave Study of Exciton Condensation in Bilayer Quantum Hall Systems

ORAL

Abstract

In bilayer two-dimensional electron systems (2DES) in GaAs a strongly correlated many-electron state forms at low temperature and high magnetic field when the total electron density $n_{T}$ becomes equal to the degeneracy of a single spin split Landau level. This state corresponds to a total filling factor $\nu_{T}=1$ and can be described in terms of pseudospin ferromagnetism, or equivalently, Bose condensation of bilayer excitons. We have simultaneously measured magneto-transport and the propagation of pulsed surface acoustic waves (SAWs) at a frequency of 747 MHz to explore the phase transition between two independent layers at $\nu_{T}=1/2+1/2$ and the correlated state at $\nu_{T}=1$ in a high quality double quantum well device. We tune through this transition by varying the total electron density in our device with front and backside electrostatic gates.

*We acknowledge funding provided by the Institute for Quantum Information and Matter, an NSF Physics Frontiers Center (NFS Grant PHY-1125565) with support of the Gordon and Betty Moore Foundation (GBMF-12500028).

–

Authors

  • J. Pollanen

    • Institute for Quantum Information and Matter and Department of Physics, California Institute of Technology, Pasadena, California 91125, USA
    • Institute for Quantum Information and Matter and Dept. of Physics, Caltech, Pasadena, CA

  • J.P. Eisenstein

    • Institute for Quantum Information and Matter and Department of Physics, California Institute of Technology, Pasadena, California 91125, USA

  • L.N. Pfeiffer

    • Department of Electrical Engineering, Princeton University, Princeton, New Jersey 08544, USA

  • K.W. West

    • Department of Electrical Engineering, Princeton University, Princeton, New Jersey 08544, USA