10 research outputs found
Dephasing time of composite fermions
We study the dephasing of fermions interacting with a fluctuating transverse
gauge field. The divergence of the imaginary part of the fermion self energy at
finite temperatures is shown to result from a breakdown of Fermi's golden rule
due to a faster than exponential decay in time. The strong dephasing affects
experiments where phase coherence is probed. This result is used to describe
the suppression of Shubnikov-de Haas (SdH) oscillations of composite fermions
(oscillations in the conductivity near the half-filled Landau level). We find
that it is important to take into account both the effect of dephasing and the
mass renormalization. We conclude that while it is possible to use the
conventional theory to extract an effective mass from the temperature
dependence of the SdH oscillations, the resulting effective mass differs from
the of the quasiparticle in Fermi liquid theory.Comment: 14 pages, RevTeX 3.0, epsf, 1 EPS figur