Measurement of the specific heat of a fractional quantum Hall system

Abstract

Using a time-resolved phonon absorption technique, we have measured the relative specific heat of a two-dimensional electron system in the fractional quantum Hall effect regime. For filling factors ν=5/3, 4/3, 2/3, 3/5, 4/7, 2/5, and 1/3 the specific heat displays a strong exponential temperature dependence in agreement with excitations across a quasiparticle gap. At filling factor ν=1/2 we were able to measure the relative specific heat of a composite fermion system. The observed nearly linear temperature dependence on temperature down to T=0.14 K agrees well with early predictions for a Fermi liquid of composite fermions. © 2007 The American Physical Society.