Zusammenfassung
A permanent magnet (spherical shape, radius 100 μm) is levitating inside a superconducting parallel plate capacitor made of YBCO. Translational oscillations of the magnet at its resonance frequency (∼150 Hz) can be excited and detected. The damping of the oscillations is investigated as a function of temperature and oscillation amplitude. Close to T c we observe a steep minimum of the damping. ...
Zusammenfassung
A permanent magnet (spherical shape, radius 100 μm) is levitating inside a superconducting parallel plate capacitor made of YBCO. Translational oscillations of the magnet at its resonance frequency (∼150 Hz) can be excited and detected. The damping of the oscillations is investigated as a function of temperature and oscillation amplitude. Close to T c we observe a steep minimum of the damping. The data can be described by a linear frictional force which decreases near T c , and a quadratic one which diverges at T c . These frictional forces are attributed to flux flow phenomena in the high‐T c superconductor.