Session S2 - High-Tc Superconductors: Scattering.
INVITED session, Wednesday afternoon, March 24
517B, Palais des Congres
We have developed a new method to study local charge inhomogeneities, based on the effect they have on the Josephson plasma resonance (JPR). The analysis of the JPR mode provides information on the local variation of the superfluid density within the CuO_2 planes, thus empowering one with a tool for "microscopy" on the superconducting condensate. Analysis of c-axis IR spectra of LSCO samples has revealed presence of regions within CuO_2 planes with the length scale of ~ 100-200 Åwithin which superconductivity is strongly depressed or completely depleted. An examination of the doping trends suggests that development of these superconducting inhomogeneities is triggered by the formation of the unidirectional spin density waves (stripes) in LSCO at x=1/8. This picture is consistent with NMR and \muSR results, but also with neutron scattering, assuming the spin-ordered signal is coming from regions of depressed superconductivity. The analysis of Josephson plasmon in YBCO doped with Zn and Ni reveals important differences these impurities have on local charge dynamics.
This work is a collaboration with D.N.Basov (UCSD), Seiky Komiya, Yoichi Ando (CRIEPI) and C.C.Homes (BNL).