Torque anisotropy due to crystal defect structure of the superconducting niobium single crystal

A mechanical method is used to study the pinning force of Abrikosov's flux lines in cylindrical niobium single crystals at different values of the applied transverse magnetic field. It is shown that a specimen deformation by compression of 40% leads to an increase of the flux line pinning. It is also shown that a force couple tearing flux lines of their pinning centres is especially large, when the direction of the magnetic field coincides with that of [110], and is relatively smaller when the field is directed along [001] or [112] in the (110) and (111) planes, respectively. Metallographic and electron microscopic analyses reveal that the cell boundaries of the single crystal and the dislocations in their limits are mainly oriented along the given directions. [Russian Text Ignored].