Flip effect in the orientation of a magnet levitating over a superconducting torus in the Meissner state

The torque between a permanent magnet and a toroidal superconductor in the Meissner state is calculated using a model previously proposed based on London’s and Maxwell’s equations. A flip effect on the stable orientation of the magnet as a function of position is demonstrated. At large distances the magnet tends to be perpendicular to the axis of the torus, but when you approach it, at a certain point there is a flip and it tends to be parallel to that axis while being closer than a certain limit. This effect can be easily used as a binary detector for proximity.

Research highlights► A torus superconductor shape has been analyzed. ► There is a flip effect on the stablest angular position of a magnet over the superconductor. ► The basis for a binary contactless proximity sensor has been presented.