Spontaneous rotation of magnets levitating above high-Tc superconductor

TL;DR

This paper investigates the spontaneous rotation of magnets levitating above high-temperature superconductors, attributing it to magnetization inhomogeneity caused by temperature gradients, and explores methods to control this rotation.

Contribution

It provides experimental evidence linking magnetization inhomogeneity to rotation and proposes control methods for the rotation frequency.

Findings

Rotation frequency depends on magnetization difference in magnet halves

Experiment confirms magnetization inhomogeneity causes rotation

Control methods for rotation frequency are proposed

Abstract

The levitation of a cylindrical permanent magnet over a high-temperature superconductor cooled by liquid nitrogen can be accompanied by spontaneous oscillations and rotation. The reason for spontaneous rotation of the magnet is magnetization inhomogeneity induced by the temperature gradient. An experiment was carried out on the levitation of Nd-Fe-B magnets over a composite high-temperature superconductor. The experimental results confirm that the rotation frequency depends on the difference in the magnetization values in the upper and lower halves of the magnet. Methods for controlling the rotation frequency of a levitating magnet are proposed.