THEORY OF THE PINNING GAP IN THE PHONON-SPECTRUM OF A DISORDERED WIGNER CRYSTAL

We present a microscopic theory for the calculation of the pinning gap and magnetophonon spectrum of a disordered Wiper crystal. Its main feature resides in the inclusion in the pinning energy of the contribution arising from distortions of the crystal on all length scales. This new contribution implies that the observed pinning pp is consistent with a domain size much larger than previously supposed. In the weak-coupling regime, and in two dimensions, a logarithmic dependence of the pinning gap on impurity potential is predicted.