This is claimed in this wonderful article [Science, 331:1579(2011)], which I have already mentioned in my yesterday's entry.
In cuprate superconductors, people observe not only one d-wave SC gap but an additional gap, which opens up at the zone boundary and at a temperature T* far above Tc. A natural question is how these two gaps are connected. Two proposed scenarios are common in the market: one takes both originating from the same source while the other associates them with respective orders. Clarifying this question paves the way to the ultimate theory of high Tc copper oxides.
Now this article provides convincing evidence, combining ARPES, Polor Ker Effect and Time Resolved Reflectivity, that, T* signals a true but somewhat rounded thermal phase transition into a non-Sc phase. Actually, their work revealed three temperatures: Tc, T* and Tg. Here the Tg is a bit higher than Tc but far below T*, indicating the pairing fluctuations. Their mean-field calculations some candidate orders suggest that the paring energy and the pseudogap energy are of the same order, raising the question if they are connected in a deeper manner.
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