BEGIN:VCALENDAR VERSION:2.0 PRODID:-//Talks.cam//talks.cam.ac.uk// X-WR-CALNAME:Talks.cam BEGIN:VEVENT SUMMARY:Is the "\;Hidden Electronic Order"\; in the Cuprates neith er Hidden nor Ordered? - J.C. Seamus Davis\, Cornell University DTSTART:20060309T021500Z DTEND:20060309T031500Z UID:TALK4666@talks.cam.ac.uk CONTACT:cb203 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 Ca_{2-x}Na_{x}CuO_{2}Cl_{2} in that regime do reveal a 4a0 X 4a0 checkerboard pattern of density-of-state modu lations which persists into the low doped superconducting region. But the actual charge density modulation in the checkerboard pattern is negligibl e.\n\nSo\, to examine the doped-hole density in Ca_{2-x}Na_{x}CuO_{2}Cl_{2 } directly\, we have recently developed new Mottness imaging techniques . We find atomic-scale variations in hole-density (primarily on the oxygen s ites) which have no long range order. Instead it looks like a hole glass w ith short range 4a0 X 4a0 correlations. Embedded in this hole glass are mo re ordered nano-regions of dimensions ~4a0 X 16a0. It seems plausible that the checkerboard density-of-state modulations are due to scattering of qu asiparticles by the Coulomb potential of this 4a0 X 4a0 correlated hole gl ass.\n\nI will discuss the relationship of these observations to results f rom other probes and argue that the electronic state in lightly-doped cupr ates has not been hidden\, merely overlooked. I will also discuss the like lihood that this type of hole glass is\, in fact\, the native state of lig htly doped cuprates (when dopant disorder is present).\n LOCATION:Pippard Lecture Theatre\, Cavendish Laboratory\, Department of Ph ysics END:VEVENT END:VCALENDAR