Experimental demonstration of Fermi surface effects at filling factor 5/2

An overview is given on surface wave acoustic (SWA) measurements that distinctly demonstrate features at 5/2 filling factor which, in similarity to findings at 1/2, indicate the presence of a composite fermion Fermi surface. These SAW propagation features at 5/2 are observed at temperatures above those at which the system forms a quantized Hall state and were derived using samples of particularly high mobility. The results may be supportive of the model of composite fermion pairing at 5/2 in which quasiparticles condense into a Moore-Read-like state.