Tunneling from a correlated two-dimensional electron system transverse to a magnetic field

We show that in a magnetic field parallel to a two-dimensional (2D) electron layer, strong electron correlations can change the rate of tunneling from the layer to the 3D continuum exponentially. It leads to a specific density dependence of the escape rate. The mechanism is a dynamical Mössbauer-type recoil, in which the Hall momentum of the tunneling electron is partly transferred to the whole electron system, depending on the interrelation between the rate of interelectron momentum exchange and the tunneling duration. We show that, in a certain temperature range, the parallel magnetic field can enhance rather than suppress the tunneling rate. The effect is due to the field induced energy exchange between the in-plane and out-of-plane motion. A parallel magnetic field can also lead to switchings between tunneling from different intra-well states, and between tunneling and thermal activation. Explicit results are obtained for a Wigner crystal. They are in qualitative and quantitative agreement with the relevant experimental data for electrons on helium, with no adjustable parameters. The theoretical results also suggest new experiments in semiconductor systems which will reveal electron correlations and their dynamical aspects.