CYCLOTRON RESONANCE IN THE FRACTIONALLY QUANTIZED 2D ELECTRON GAS.

Abstract

In a charge density wave or Wigner crystalline state of a two dimensional electron gas (2DEG) an upward shift of the cyclotron frequency, associated with pinning to a lattice bound potential, is expected. We have attempted to probe the enigmatic fractionally quantized state by concurrently measuring cyclotron resonance and magnetotransport of a high mobility 2DEG in a high magnetic field (approx. 200kG) and at low temperature (0. 4K) and filling factor (approx. 0. 2). We do not observe any cyclotron resonance shift associated with the nu equals 1/3 state - a result which is consistent with the idea that the fractionally quantized states are incompressible and as such cannot be pinned. We observe a gradual shift of the resonance, as a function of filling factor, which appears to be due to an enhancement of the electron-LO phonon interaction with increasing electron confinement perpendicular to the interface.