Y. Zhang*, P. W. Anderson*, D. Bonn**, R. Liang**, W. N. Hardy**,
Z. Xu*$, Y. Wang* , T. Kageshita@ and S. Uchida@,

*Department of Physics, Princeton University.
**Department of Physics, Univ. British Columbia.
@School of Frontier Sciences, University of Tokyo.
$Present address: Zhejiang University, Hangzhou, China.