Phonon-mediated drag at $\nu=1/2$: A test of the Chern-Simons composite   fermion theory
  We report on a study of the phonon-mediated frictional drag between two-dimensional electron layers at the Landau level filling factor $\nu=1/2$ predicted by Chern-Simons composite-fermion theory. Frictional drag between widely spaced layers is dominated by the phonon-mediated interaction and is altered from its zero-field form because of the large composite-fermion effective mass and, less strongly, by magnetic local-field effects. We find that the reduced drag resistance $\rho(T)/T^2$ peaks at a larger temperature and has a different density dependence than at zero field. We compare these results with recent experimental findings. 
Martin C. Bonsager, Yong Baek Kim, and A. H. MacDonald