Triple approach to determination of the caxis penetration depth in BSCCO crystals
Abstract
The caxis penetration depth $\lambda_c$ in Bi$_2$Sr$_2$CaCu$_2$O$_{8+\delta}$ (BSCCO) single crystals as a function of temperature has been determined using three highfrequency techniques, namely: (i) measurements of the acsusceptibility at a frequency of 100 kHz for different sample alignments with respect to the ac magnetic field; (ii) measurements of the surface impedance in both superconducting and normal states of BSCCO crystals at 9.4 GHz; (iii) measurements of the surface barrier field $H_J(T)\propto 1/\lambda_c(T)$ at which Josephson vortices penetrate into the sample. Careful analysis of these measurements, including both numerical solution of the electrodynamic problem of the magnetic field distribution in an anisotropic plate at an arbitrary temperature and influence of defects in the sample, has allowed us to estimate $\lambda_c(0)\approx 50 \mu$m in BSCCO crystals overdoped with oxygen ($T_c\approx 84$ K) and $\lambda_c(0)\approx 150 \mu$m at the optimal doping level ($T_c\approx 90$ K). The results obtained by different techniques are in reasonable agreement.
 Publication:

arXiv eprints
 Pub Date:
 June 2000
 arXiv:
 arXiv:condmat/0006371
 Bibcode:
 2000cond.mat..6371T
 Keywords:

 Condensed Matter  Superconductivity
 EPrint:
 8 pages, 8 figures