### Title, author, abstract

title
LONGITUDINAL ELASTIC CORRELATION LENGTH OF FLUX LINES ALONG THE $c$-AXIS NEAR THE PEAK FIELD IN Bi-2212 SINGLE CRYSTAL
authors
M. Kiuchi, H. Yamato, T. Matsushita
Department of Computer Science and Electronics, Kyushu Institute of Technology,
680--4 Kawazu, Iizuka, 820 JAPAN
abstract
The longitudinal elastic correlation length, $l_{\rm 44}$, of flux lines in a single crystal Bi-2212 superconductor is measured in the vicinity of the peak field using the Campbell method with the magnetic field parallel to the $c$-axis. It is found that $l_{\rm 44}$ in this region is of the order of $1~\mu$m and much longer than the distance between the CuO$_{2}$ layers. In addition, $l_{\rm 44}$ depends on the magnetic field and temperature. These results agree well with the pinning correlation length estimated using the measured critical current density, $J_{\rm c}$. The apparent pinning potential estimated from the magnetic relaxation measurement takes a peak near the peak field and agrees well with the result of collective flux creep theory in which the obtained $J_{\rm c}$ and $l_{\rm 44}$ are used. It is concluded from these results that the flux lines are strongly coupled over a fairly long distance along the $c$-axis even in the vicinity of peak field.
Original paper appears in
9th International Symposium on Superconductivity
October 21--25, 1996
Sapporo, Hokkaido, Japan