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SUMMARY:Is the Hidden Electronic Order in the Cuprates neither Hidden nor 
 Ordered? - Prof. J. C. Samus Davis\, Cornell University
DTSTART:20060309T141500Z
DTEND:20060309T151500Z
UID:TALK4644@talks.cam.ac.uk
CONTACT:Duncan Simpson
DESCRIPTION:Does a hidden ordered electronic state exist in the underdoped
  pseudogap regime of the cuprate phase diagram? This question has been the
  focus of intensive research worldwide. But after more than a decade of se
 arches\, no long range ordered state has ever been detected there. \n\nOur
  spectroscopic imaging STM studies of Ca2-xNaxCuO 2Cl2 in that regime do r
 eveal a 4a0X4a0 checkerboard pattern of density-of-state modulations  whic
 h persists into the low doped superconducting region. But the actual charg
 e density modulation in the checkerboard pattern is negligible.\n\nSo\, to
  examine the doped-hole density in Ca2-xNaxCuO 2Cl2 directly\, we have rec
 ently developed new Mottness imaging techniques . We find atomic-scale var
 iations in hole-density (primarily on the oxygen sites) which have no long
  range order. Instead it looks like a hole glass with short range 4a0X4a0 
 correlations. Embedded in this hole glass are more ordered nano-regions of
  dimensions ~4a0X16a0. It seems plausible that the checkerboard density-of
 -state modulations are due to scattering of quasiparticles by the Coulomb 
 potential of this 4a0X4a0 correlated hole glass.\n\nI will discuss the rel
 ationship of these observations to results from other probes and argue tha
 t the electronic state in lightly-doped cuprates has not been hidden\, mer
 ely overlooked. I will also discuss the likelihood that this type of hole 
 glass is\, in fact\, the native state of lightly doped cuprates  (when dop
 ant disorder is present).\n
LOCATION:Pippard Lecture Theatre\, Cavendish Laboratory
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