Hydrodynamics of the quantum Hall smectics

We propose a dynamical theory of the stripe phase arising in a two-dimensional electron liquid near half-integral fillings of high Landau levels. The system is modelled as a novel type of a smectic liquid crystal with the Lorentz force dominated dynamics. We calculate the structure factor, the dispersion relation of the collective modes (magnetophonons), and their intrinsic attenuation rate. We find strong power-law renormalizations of the elastic and dissipative coefficients by thermal fluctuations familiar from the conventional smectics but with different dynamical scaling exponents.