Enhancement of tunneling from a correlated 2D electron system by a   many-electron Mossbauer-type recoil in a magnetic field
  We consider the effect of electron correlations on tunneling from a 2D electron layer in a magnetic field parallel to the layer. A tunneling electron can exchange its momentum with other electrons, which leads to an exponential increase of the tunneling rate compared to the single-electron approximation. Explicit results are obtained for a Wigner crystal. They provide a qualitative and quantitative explanation of the data on electrons on helium. We also discuss tunneling in semiconductor heterostructures. 
M. I. Dykman, T. Sharpee, and P. M. Platzman