Meissner levitation of a millimeter size neodymium magnet within a superconducting radio frequency cavity

TL;DR

This paper demonstrates the first experimental levitation of a millimeter-sized neodymium magnet inside a superconducting RF cavity, opening new possibilities for optomechanical systems.

Contribution

It reports the first successful magnetic levitation of a magnet within an SRF cavity, advancing the development of novel optomechanical devices.

Findings

Magnet levitation is stable over multiple thermal cycles.

Magnetic field exceeds aluminum's critical field by 140 times.

Experimental setup achieves levitation within a 10 GHz SRF cavity.

Abstract

We report on the magnetic levitation of a millimeter sized neodymium permanent magnet within the interior of a superconducting radio frequency (SRF) cavity. To the best of our knowledge, this is the first experimental work on levitating a magnet within an SRF cavity. The cavity is a coaxial quarter wave microwave resonator made from 6061 aluminum, having a resonance frequency of 10GHz and a loaded Q of 1400. The cylindrical magnet (N50) has a height of 1 mm, a diameter of 0.75 mm, a mass of 4 mg, and a remanence of 1.44 T. This produces a peak magnetic field 140 times greater than the critical field of aluminum. Our measurements are consistent over several heating and cooling cycles. Our work provides a path towards a novel optomechanical system.