J. Phys. IV France 12 (2002) Pr9-155
DOI: 10.1051/jp4:20020383

Microscopic investigation of moving flux line structures in superconductors using neutron diffraction and SR

E.M. Forgan¹, D. Charalambous¹, D. Fort², R. Cubitt³, Ch. Simon⁴, S.L. Lee⁵ and A. Amato<sup>6

1</sup>  School of Physics & Astronomy, University of Birmingham, Birmingham B15 2TT, U.K.
²  School of Metallurgy & Materials, University of Birmingham, Birmingham E15 2TT, U.K.
³  Institut Laue-Langevin, 38042 Grenoble, France
⁴  Laboratoire CRISMAT, ISMRA, 14050 Caen, France
⁵  School of Physics & Astronomy, University of St. Andrews, St. Andrews KY16 SSS, U.K.
⁶  Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland

Abstract
We have used a variety of microscopic techniques to reveal the structure and motion of flux line arrangements, while the flux lines are caused to move by a transport current. Using small-angle neutron scattering, we are able to demonstrate direaly the alignment of the nearest-neighbour direction of flux lines while they are moving. The results are similar but not identical to those from two-dimensional simulations. We also see the destruction of the flux lattice by plastic flow and the bending of flux lines. We have also employed SR, which measures the distribution of field values within the mixed state, to obtain information about the speed and degree of order of the motion of flux lines past the muons. Such measurements give complementary information to that obtained by neutron techniques. The general aspects of these measurements, of interest to those working in other areas, are the creation of order in non-equilibrium situations and the interplay of the ordering cccuning during dissipation and the ordering caused by the crystal structure of the superconductor which is host to the flux lines.

© EDP Sciences 2002