ELASTIC PROPERTIES OF FLUX-LINE ARRAYS IN HIGH TRANSITION-TEMPERATURESUPERCONDUCTORS PROBED BY 2-SIDED DECORATION

The elastic constants of magnetic flux-line lattices in copper oxide s uperconductors have remained uncharacterized despite their essential r ole in determining important phenomena such as melting. Here the absol ute values of the elastic moduli of flux-line arrays have been probed by correlating the positions of individual flux lines emerging from op posite sides of Bi2Sr2CaCu2O8 (BSCCO) superconductors. These experimen ts demonstrate that the compressional and shear moduli of the flux-lin e lattice are three orders of magnitude smaller than the values predic ted by standard models. The origin of these changes in the moduli and the general applicability of this approach to other materials are disc ussed. In addition, there is a remarkable correspondence between the e xcitations of the flux-line arrays and those of superfluid helium.