The effect of magnetic flux creep on the lift force in a magnet/superconductor system was studied. It was shown experimentally that in the case of real levitation (when a levitating object bears only on a magnetic field) the suspension height and consequently the lift force did not change over a long period of time. When the levitating object is fixed for some time (i.e. a rigid constraint is imposed on it), the levitation height decreases after removal of the external constraint. It is assumed that free oscillations of the levitating object slow down the flux creep process, which is activated when these oscillations are suppressed.
The effect of the suppression of flux creep in a high-temperature superconductor by counter forces exerted on the vortex ends was studied. These forces, acting in the opposite direction to the process of vortex diffusion, arise when the magnetized sample is put into a nonuniform magnetic field. The source of the field should be placed near the surface of the superconductor where the flux line ends are located. The critical states in a disk sample placed near a ferromagnet or permanent magnets were calculated. The results of the calculations verify the bipolar current structure and, therefore, the existence of counter Lorentz forces in the near-surface region. It was shown that in addition to the Lorentz force it is necessary to take into account the magnetic force acting on the vortex ends in the external nonuniform magnetic field. Depending on the direction of this force, the magnetic relaxation slows down or accelerates.
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