Using Corbino samples we have observed oscillatory conductance in a high-mobility two-dimensional electron system subjected to crossed microwave and magnetic fields. On the strongest of the oscillation minima the conductance is found to be vanishingly small, possibly indicating an insulating state associated with these minima.
@article{arxiv.cond-mat/0303472,
title = {Observation of Apparently Zero-Conductance States in Corbino Samples},
author = {C. L. Yang and M. A. Zudov and T. A. Knuuttila and R. R. Du and L. N. Pfeiffer and K. W. West},
journal= {arXiv preprint arXiv:cond-mat/0303472},
year = {2007}
}