At a very low temperature of 9mK, electrons in the 2nd Landau level of an extremely high mobility two-dimensional electron system exhibit a very complex electronic behavior. With varying filling factor, quantum liquids of different origins compete with several insulating phases leading to an irregular pattern in the transport parameters. We observe a fully developed ν=2+2/5 state separated from the even-denominator ν=2+1/2 state by an insulating phase and a ν=2+2/7 and ν=2+1/5 state surrounded by such phases. A developing plateau at ν=2+3/8 points to the existence of other even-denominator states.
@article{arxiv.cond-mat/0406724,
title = {Electron correlation in the second Landau level; a competition between many, nearly degenerate quantum phases},
author = {J. S. Xia and W. Pan and C. L. Vincente and E. D. Adams and N. S. Sullivan and H. L. Stormer and D. C. Tsui and L. N. Pfeiffer and K. W. Baldwin and K. W. West},
journal= {arXiv preprint arXiv:cond-mat/0406724},
year = {2009}
}