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SUMMARY:Some Controversial Issues in High Tc Superconductivity - a Specifi
 c Heat Perpective - Dr. John Loram (University of Cambridge)
DTSTART:20070117T111500Z
DTEND:20070117T121500Z
UID:TALK6350@talks.cam.ac.uk
CONTACT:Michael Sutherland
DESCRIPTION:After 20 years of study many important issues relating to high
 -Tc cuprate\nsuperconductivity (SC) remain unresolved. This is largely due
  to a lack of\nagreement on the nature of the normal state from which SC d
 evelops\, and in\nparticular the origin of the normal state pseudogap at l
 ow hole doping (p).\nFrom our specific heat measurements we find a univers
 al progression with p\nfrom insulator to overdoped metal via a states-non-
 conserving and\nT-independent pseudogap in the qp DOS. This gap shrinks as
  new spectral\nweight (~ 1 state per doped hole) appears near EF and close
 s abruptly close\nto optimal doping accompanied by a striking increase in 
 SC condensation\nenergy. These features are not compatible with theories o
 f the pseudogap in\nterms of a competing order parameter\, precursor SC fl
 uctuations or a spinon\ngap in spin-charge separation theories.\n\n
LOCATION:Mott Seminar Room\, Cavendish Laboratory\, Department of Physics
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