THERMAL COLLAPSE OF THE FRACTIONAL QUANTUM-HALL-EFFECT ENERGY GAPS

The relationship between the mean energy of a two-dimensional electron gas and the first moment of their radiative recombination is investigated in the regimes of the integer and fractional quantum Hall effects. It is shown that the magnetic-field dependence of the first moment provides a method to measure the cyclotron, enhanced spin and quasi-particle energy gaps at the same time. This allows for a comparative analysis of the temperature dependence of these gaps. Upon increasing temperature an abrupt thermal collapse is observed for those energy gaps which are associated with electron-electron interactions.