A new technique has been developed to remove flux quanta trapped in superconducting film. It consists of measuring the magnetic field distribution over a superconductor with an rf superconducting quantum interference device (SQUID) and removing the detected trapped flux using laser beam scanning. The trapped flux movement follows the motion of the Ar laser beam exactly. By scanning the laser beam over the trapped flux quanta, the trapped flux is successfully moved to any desired location. Comparison with heat flushing method, the most important advantages of this technique are (i) the flux movement in the superconducting film can be controlled precisely; (ii) by adjusting the laser power so as to change the diameter of the normal hot spot, flux creations caused by the thermoelectric potential of the material can be avoided. These results show that our technique is very useful in the field of Josephson junction electronics and other areas that require extremely low magnetic field environment.

Topics
Superconducting quantum interference device, Superconducting devices, Superconducting films, Superconductors, Tectonophysics, Lasers
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© 1992 American Institute of Physics.
1992
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