Strongly nonlinear magnetization above Tc inLu Li1, Yayu Wang1, M. J. Naughton2, S. Ono3, Yoichi Ando3 and N. P. Ong1
1 Department of Physics, Princeton University - NJ 08544, USA
2 Department of Physics, Boston College - Chestnut Hill, MA 02467, USA
3 Central Research Institute of Electric Power Industry Komae, Tokyo 201-8511, Japan
received 26 July 2005; accepted 12 September 2005
published online 5 October 2005
Using high-resolution magnetometry we have investigated in detail the magnetization M above the critical temperature Tc in . In a broad range of temperature T above Tc, we find that M(T,H) is strongly non-linear in the field H. We show that as , the susceptibility diverges to very large values ( ) if measured in weak H. In addition, M(H) displays an anomalous non-analytic form in weak fields with a strongly T-dependent exponent . These features strongly support the proposal that, above Tc, the pair condensate survives to support significant London rigidity.
74.72.-h - Cuprate superconductors (high- and insulating parent compounds).
74.25.Ha - Magnetic properties of superconductors.
74.25.Dw - Superconductivity phase diagrams.
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