Dynamics of a Ferromagnetic Particle Levitated over a Superconductor

Under conditions where the angular momentum of a ferromagnetic particle is dominated by intrinsic spin, applied torque is predicted to cause gyroscopic precession of the particle. If the particle is sufficiently isolated from the environment, a measurement of spin precession can potentially yield sensitivity to torque beyond the standard quantum limit. Levitation of a micron-scale ferromagnetic particle above a superconductor is a possible method for near-frictionless suspension enabling observation of ferromagnetic particle precession and ultrasensitive torque measurements. We experimentally investigate multiple instances of a micron-scale ferromagnetic particle levitated above a superconducting niobium surface. We find that the levitating particle is trapped in a potential minimum associated with residual magnetic flux pinned by the superconductor and, using an optical technique, characterize the dynamics of the particle in such a trap.