In-plane anisotropy and possible chain contribution to magnetoconductivityin YBa2Cu3O7-delta - art. no. 224518

The magnetoresistivity of untwinned YBa2Cu3O7-delta Single crystals was mea sured in magnetic fields up to 12 T-c for B parallel toc and B parallel to ab. at temperatures up to T-c + 84 K and T-c + 50 K, respectively. Two issu es were addressed; determination of the in-plane coherence length anisotrop y gamma=xi (b)/xi (a) and discussion of the role of the CuO chains in the m agnetoconductivity Delta sigma. A fluctuation conductivity theory that allo ws for an in-plane coherence length anisotropy (xi (a)not equal xi (b)) as well as an extension of the usual Aronov-Hikami-Larkin theory that does not , were used in analyses. The results suggest that the anisotropy gamma is c lose to 1. The analyses also suggest a contribution to the magnetoconductiv ity from the CuO chains of a sign which depends on the direction between he ld and current.