The structure of the magnetic induction jumps in Bi2Sr2CaCu2O8 
monocrystal at an avalanche process

V.V. Chabanenko1, A. Nabialek2, S. Vasiliev2, H. Szymczak2, 
S. Piechota2, V.F. Rusakov3, O.A. Mironov4

1 Physico-Technical Institute NAS, 83114 Donetsk, 72 R. Luxemburg str., Ukraine
2 Institute of Physics, Polish Academy of Sciences, Al. Lotnikow 32/46, 0-668 Warsaw, Poland
3 Donetsk National University, 83055, Donetsk, 24 Universitetskaya str., Ukraine
4 Department of Physics, University of Warwick, Coventry CV4 7AL, United Kingdom

Recently [1] we monitored a thresholds for enter and for exit of the huge flux avalanches and oscillations of the magnetic induction Bsurf at the surface of the sample as a result of the huge flux avalanche in low temperature superconductors (Nb, Nb-Ti). Here we examined the structure of flux jumps in Bi2Sr2CaCu2O8 monocrystal with the aid of Hall sensor. It was placed in the centre of the sample surface. The size of the sample is 3.2x3x1mm3. Magnetic field H was directed along the small size side of the sample. All flux jumps are complete (they touch the line BSURF=0H, see figure) at 4.2K and 2K. Here we observed weak thresholds for enter and exit of magnetic flux as well as in LTSC. As we can see there is a sharp peak of induction on the flux step. Such behaviour of BSURF vs time is poorly understood. We tentatively associate the pulse shape fashion with the complicated flux dynamics and the sharp, intricate changing of current line, which are defined by thermal properties [2] of vortex material. The surface and geometrical barriers may compete with bulk pinning in determining the avalanche dynamics of vortex matter too [3].

1.	V.V. Chabanenko, V.F. Rusakov, A. Nabialek, S. Piechota, S. Vasiliev, H. Szymczak, Physica C, 369, (2002) 77.
2.	C.J. van der Beek, S. Colson, M.V. Indenbom, and M. Konczykowski, cond-mat/9912276 15 Dec 1999.
Y. Paltiel, D.T. Fuchs, E. Zeldov, Y.N. Myasoedov, H. Shtrikman, M.I. Rappaport, E.Y. Andrei, Phys. Rev. B, 58 (1998) R14763.