Experimental Demonstration of Fermi Surface Effects at Filling Factor 5/2
11 February 2002
Using small wavelength surface acoustic waves (SAW) on ultra- high mobility heterostructures, Fermi surface properties are detected at 5/2 filling factor at temperatures higher than those at which the quantum Hall state forms.
An enhanced conductivity is observed at 5/2 by employing sub 0.5microns SAW, indicating a quasiparticle mean free path substantially smaller than that in the lowest Landau level. These findings are consistent with the presence of a filled Fermi sea of composite fermions, which may pair at lower temperatures to form the 5/2 ground state.