Ballistic Heating of a Two-Dimensional Electron System by Phonon Excitation of the Magnetoroton Minimum at <span class="aps-inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi mathvariant="italic">ν</mi><mspace></mspace><mo>=</mo><mspace></mspace><mn>1</mn><mn></mn><mi>/</mi><mn>3</mn></math></span>

U. Zeitler; A. M. Devitt; J. E. Digby; C. J. Mellor; A. J. Kent; K. A. Benedict; T. Cheng

doi:10.1103/PhysRevLett.82.5333

Ballistic Heating of a Two-Dimensional Electron System by Phonon Excitation of the Magnetoroton Minimum at $ν = 1 / 3$

U. Zeitler, A. M. Devitt, J. E. Digby, C. J. Mellor, A. J. Kent, K. A. Benedict, and T. Cheng

Phys. Rev. Lett. 82, 5333 – Published 28 June 1999

Abstract

A two-dimensional electron system (2DES) is excited with ballistic phonons. Using the 2DES as a thermometer we directly measure the specific heat of the electron system. At a Landau level filling factor $ν = 1 / 3$ we deduce a strongly reduced specific heat compared to $ν = 1 / 2$ which we can assign to a small but finite density of states in the fractional quantum Hall gap. Furthermore, at $ν = 1 / 3$ the phonons are shown to excite finite wave vector magnetorotons across a gap, in excellent agreement with theoretical predictions.

Received 3 November 1998

DOI:https://doi.org/10.1103/PhysRevLett.82.5333

Authors & Affiliations

U. Zeitler^*, A. M. Devitt, J. E. Digby, C. J. Mellor, A. J. Kent, K. A. Benedict, and T. Cheng

School of Physics and Astronomy, University of Nottingham, Nottingham, NG7 2RD, United Kingdom

^*Present address: Institut für Festkörperphysik, Universität Hannover, Appelstraße 2, D-30167 Hannover, Germany.Email address: zeitler@nano.uni-hannover.de