### Ginzburg-Landau parameter in YBa{sub 2}Cu{sub 3}O{sub 6.95} below the irreversibility temperature as measured by {mu}{sup +}SR in high magnetic fieldsGinzburg-Landau parameter in YBa{sub 2}Cu{sub 3}O{sub 6.95} below the irreversibility temperature as measured by {mu}{sup +}SR in high magnetic fields

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 Author Riseman, T. M. ♦ Brewer, J. H. ♦ Chow, K. H. ♦ Hardy, W. N. ♦ Kiefl, R. F. ♦ Kreitzman, S. R. ♦ Liang, R. ♦ MacFarlane, W. A. ♦ Mendels, P. ♦ Morris, G. D. ♦ Rammer, J. ♦ Schneider, J. W. ♦ Niedermayer, C. ♦ Lee, S. L. Source United States Department of Energy Office of Scientific and Technical Information Content type Text Language English
 Subject Keyword PHYSICS ♦ HIGH-TC SUPERCONDUCTORS ♦ GINZBURG-LANDAU THEORY ♦ COPPER OXIDES ♦ BARIUM OXIDES ♦ YTTRIUM OXIDES ♦ MAGNETIC FLUX ♦ TYPE-II SUPERCONDUCTORS ♦ MUON SPIN RELAXATION ♦ MAGNETIC FIELDS ♦ PENETRATION DEPTH ♦ COHERENCE LENGTH ♦ TEMPERATURE DEPENDENCE Abstract The vortex state of a type-II superconductor produces a distinctive {mu}{sup +}SR line shape with features determined by the average internal field {ital B}{sub {ital o}}, the magnetic penetration depth {lambda}, the superconducting coherence length {xi}, and the degree of disorder in the vortex lattice. Only in the high field regime ({lambda}{much_gt}{ital L}{gt}{xi}, where {ital L} is the intervortex spacing) do the vortex cores (of radius {approx}{xi}) occupy a large enough area that they are observable in the line shape as a high field cutoff. Our {mu}{sup +}SR measurements of the field distributions in a mosaic of single crystals of YBa{sub 2}Cu{sub 3}O{sub 6.95} in fields of 1.9, 4.1, 4.7, and 6.5 T ({bold B}{sub {ital o}}{equivalent_to}{ital c}) are the measurements by {mu}SR or NMR in a high-{ital T}{sub {ital c}} superconductor which show all the features of the line shape. We find {lambda}=0.15{plus_minus}0.01 {mu}m at 10 K and the Ginzburg-Landau parameter {kappa}{equivalent_to}{lambda}/{xi}=69.6{plus_minus}1.4 constant between 30 and 75 K; this is the only measurement to date of {kappa} in YBa{sub 2}Cu{sub 3}O{sub 6.95} below the irreversibility temperature. Due to disorder in the vortex lattice, either from pinning or from vortex fluctuations that are quasistatic on the time scale of {mu}{sup +}SR, the observed line shape is smeared relative to that predicted for a perfect lattice. From the degree of smearing, we estimate an upper limit of 5.5% for the rms deviation of individual vortices from their ideal positions. ISSN 01631829 Educational Use Research Learning Resource Type Article Publisher Date 1995-10-01 Publisher Place United States Journal Physical Review, B: Condensed Matter Volume Number 52 Issue Number 14