A Macroscopic Magnet Precesses while in gyroscopic motion

Amazing stuff! Among others, Albert Einstein worked on this subject (see references).

"In 1861, physicist James Clerk Maxwell proposed that a magnet behaves to some extent like a spinning gyroscope, but his experiments never managed to demonstrate the effect. Since then, researchers have observed various manifestations of so-called gyromagnetism, mostly in specialized magnetic materials or with spinning magnets,

but now a research team has detected signatures of gyroscopic motion corresponding to Maxwell’s original ideas. The team used a microscopic magnetic sphere in a technique that, with improvements, could be employed for ultrasensitive magnetic-field detection, which could be useful for research on biological magnetism.

If you try to tilt a gyroscope spinning around a vertical axis, it will respond by tilting at 90° from the push direction, an effect that leads to precession in response to gravity—such as the slow loop executed by the axis of a spinning top.

An electron in a magnetic field behaves like a gyroscope in a gravitational field because the electron has a magnetic moment, which is associated with intrinsic angular momentum, or spin.

So you might expect that a material whose microscopic spins align—such as an ordinary ferromagnet—would have a macroscopic angular momentum and behave like a gyroscope. ...

Armed with much smaller magnets—spheres 40–60 µm in diameter ... They levitated a magnet by placing it inside a 2.5-mm-diameter hole bored into a piece of lead chilled below its superconducting transition temperature. Superconductors expel magnetic fields, so they can form stable magnetic traps. In this experiment, at equilibrium, the magnet’s magnetic moment aligns with a small, nearly horizontal field present in the trap. Following an excitation by the field, the magnet oscillates around its aligned equilibrium orientation for some 20 seconds.

The magnet’s motion can be excited into either of two perpendicular oscillations, horizontal and vertical, with distinct frequencies. But the magnet’s intrinsic angular momentum should generate precession that turns the two oscillations’ otherwise linear trajectories into narrow ellipses.

To detect these subtle motions, ... placed two extremely sensitive magnetometers above the levitated magnet, each sensitive to one of the two oscillation modes. By analyzing the two signals, the team determined the tiny amount of intrinsic angular momentum associated with the sphere’s magnetic moment. They also determined the sphere’s g factor, a number proportional to the ratio of a particle’s magnetic moment to its intrinsic angular momentum. The values determined for several spheres were within about 10% of the team’s estimates based on a simple theory accounting for the magnets’ sizes and composition. ...

that previous work has found similar effects in the oscillation of optically levitated nanoparticles driven either by an external force or by thermal noise. But demonstrating gyromagnetism that arises from the total internal spin of a particle “has eluded researchers for a very long time,” ..."

From the abstract:

"A nonspinning permanent ferromagnet is predicted to behave as a gyroscope at sufficiently low frequencies, which can be seen as a manifestation of gyromagnetism.

This yet unexplored regime, conjectured for the first time by Maxwell [A Treatise on Electricity and Magnetism (... 1873).], has recently been proposed for ultrasensitive magnetometry and for atomic like quantum stabilization of a levitated nanomagnet in a static field.

Here, we observe signatures of gyroscopic effects in the rotational dynamics of a nonspinning permanent ferromagnet levitated in a superconducting trap. Specifically, we detect spin-rotation coupling between different librational modes, leading to elliptical trajectories, in good agreement with theoretical predictions. From our measurements, we can infer both the intrinsic angular momentum of the levitated magnet and its gyromagnetic 𝑔"

Physics - A Macroscopic Magnet Precesses "An isolated magnet’s intrinsic angular momentum induces gyroscopic motion, an observation that could lead to ultrasensitive magnetometers."

Observation of Gyroscopic Coupling in a Nonspinning Levitated Ferromagnet (open access)

Spin around. The magnetic moment (orange arrow) of a levitated magnetic microsphere (black) executes elliptical motion (green and blue loops) in the presence of a magnetic field (not shown). In the absence of the gyromagnetic effects that arise from the magnet’s intrinsic angular momentum, the motions would be linear.