Abstract
Fractional quantum-Hall-effect features around filling factor nu = 1/2
have been analyzed using the composite-fermion approach. Effective
masses deduced from the temperature dependence of the Shubnikov-de Haas
(SdH) oscillations, in agreement with other measurements, show a divergence as the filling factor approaches nu = 1/2 and scale as
(density)(1/2). The magnetic-field dependence of the amplitude is
explained quantitatively in terms of normal impurity scattering and a
strong dephasing term associated with density inhomogeneities of order
0.5%. It is pointed out that assumptions made in the derivation of the
standard theory used to analyze SdH oscillations are less likely to be
satisfied for composite fermions and that some caution should therefore
be used in interpreting effective-mass results obtained in this way.
Users
Please
log in to take part in the discussion (add own reviews or comments).