Deformation-Induced Anistropy of the Critical Current in Single Crystal Niobium,
CORNELL UNIV ITHACA N Y MATERIALS SCIENCE CENTER
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Anisotropy of the critical current in a 110 niobium single crystal of very high purity is observed to result from tensile deformation. The critical current exhibits local maxima when the magnetic field is directed along the 1,-1,0 and 001 directions. The height of the 1,-1,0 maximum increases with respect to the height of 001 maximum as the magnetic field is decreased. The 001 maximum is sensitive to the condition of the sample surface and exhibits rectification. There is a contribution to the anisotropy of the as-deformed crystal caused by anisotropic surface roughness, which can be removed by chemical polishing. The effect of the interaction at the surface is thought to be magnified by the decrease in the flux line lattice shear modulus C66 in that region.
- Solid State Physics