Heat capacity of a 2DEG

E. Grivei, J. M. Beuken, G. Mariage, V. Bayot, M. Shayegan

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Abstract

We review recent heat capacity experiments performed on GaAs/AlGaAs heterostructures containing two-dimensional electron layers. Near v=1, the strong coupling to the nuclear spin system attributed to Skyrmion-induced low-energy spin excitations has a dramatic effect on the heat capacity which rises by orders of magnitude. We show that this giant heat capacity is consistent with the Schottky nuclear heat capacity of Ga and As atoms in the quantum wells, except at very low temperature where heat capacity exhibits a remarkably sharp peak suggestive of a phase transition in the electronic system. We also report quasi-adiabatic experiments providing quantitative evidence that the sharp peak in heat capacity is due to an enhanced nuclear-spin diffusion from the GaAs quantum wells into the AlGaAs barriers. Finally, we present the latest heat capacity results which probe the presence or the absence of Skyrmions at large Zeeman energy.

Original languageEnglish (US)
Pages (from-to)90-96
Number of pages7
JournalPhysica B: Condensed Matter
Volume256-258
DOIs
StatePublished - Dec 2 1998

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Electrical and Electronic Engineering

Keywords

  • Heat capacity
  • Nuclear spins
  • Phase transition
  • Skyrmions

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    Grivei, E., Beuken, J. M., Mariage, G., Bayot, V., & Shayegan, M. (1998). Heat capacity of a 2DEG. Physica B: Condensed Matter, 256-258, 90-96. https://doi.org/10.1016/S0921-4526(98)00568-7