The magnetic flux-drag torque between a small permanent magnet with off-axis circular motion and an epoxy-high-Tcsuperconducting sample with different weighting ratio were measured by a homemade vertical torsion balance. It was found that the magnetic flux-drag torques scaled to a good approximation with the mass of the superconductor inside the superconducting sample. A simple model with the Bean's critical state approximation is then introduced to explain the functional dependence of the magnetic flux-drag torque against the distance between the rotating magnet and the epoxy-superconductor sample. Results of calculation agree with experimental measurements quite closely.
Physica C: Superconductivity and its Applications 252(1-2), pp.203-207