Conductivity-peak broadening in the quantum Hall regime

We argue that hopping conductivity dominates on both sides of σₓₓ peaks in low-mobility samples and use a theory of hopping of interacting electrons to estimate a width {Δ}{ν} of the peaks. Explicit expressions for {Δ}{ν} as a function of the temperature T, current J, and frequency {ω} are found. It is shown that {Δ}{ν} grows with T as (T/T₁{)}^{{{κ}}}, where κ is the inverse-localization-length exponent. The current J is shown to affect the peak width like the effective temperature{T}eff(J)∝{J}1/2$ if ${T}eff(J)T. The broadening of the Ohmic ac-conductivity peaks with frequency ω is found to be determined by the effective temperature{T}eff(ω)~ω/{k}B$.