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SUMMARY:Superconducting phase and pseudogap in the high-temperature cuprat
 e superconductors. - Patrick Rourke\, University of Bristol
DTSTART:20120425T101500Z
DTEND:20120425T111500Z
UID:TALK37695@talks.cam.ac.uk
CONTACT:Michael Sutherland
DESCRIPTION:In underdoped cuprate superconductors\, phase stiffness is low
  and\nlong-range superconducting order is easily wiped out by thermally-ge
 nerated vortices. This gives rise to a broad temperature regime above the 
 zero-resistive state in which the superconducting phase is incoherent.\n\n
 It has often been suggested that these vortex-like excitations are\nrelate
 d to the normal-state pseudogap\, with the pseudogap described as a kind o
 f precursor superconducting pairing. However\, to determine the precise re
 lationship between the pseudogap and superconductivity\, it is important t
 o establish whether the broad phase-fluctuation regime vanishes\, along wi
 th the pseudogap\, in the slightly overdoped region of the phase diagram.\
 n\nI will present measurements tracking the restoration of the normal-stat
 e magnetoresistance in overdoped La_(2-x)Sr_(x)CuO_(4)\,\nthat show that t
 he phase-fluctuation regime remains broad across the entire superconductin
 g composition range [1]. This universal low phase stiffness is correlated 
 with a low superfluid density\, a characteristic of both underdoped and ov
 erdoped cuprates. The formation of the pseudogap\, by inference\, is there
 fore both\nindependent of and distinct from superconductivity.\n\n[1] P.M.
 C. Rourke et al.\, Nature Physics 7\, 455 (2011).
LOCATION:Mott Seminar Room\, Cavendish Laboratory\, Department of Physics
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