Diamagnetic levitation of water realized with a simple device consisting of ordinary permanent magnets

Diamagnetic levitation is an appealing technique for levitating objects at room temperature without subjecting the sample to potentially damaging control fields, such as high-intensity laser light or sound pressure. However, owing to the extremely low magnetic susceptibility of diamagnetic materials, except for bismuth and graphite, diamagnetic levitation generally necessitates the use of exceptionally strong magnets, such as those found in world-class high-field facilities. This study simulated the magnetic field distribution in a narrow valley formed between two adjacent rectangular cuboid magnets with antiparallel magnetizations, at a spatial resolution of 5 μm. The simulations indicated the generation of a strong magnetic force field, $B∂B/∂z(>40 000 T2/m)$⁠, which could lift not only light organic compounds but also dense metallic compounds. Moreover, the addition of another pair of smaller sized magnets provided a local potential minimum that satisfied the conditions for non-contact levitation. Based on these results, a compact magnetic levitation system was developed by combining four small commercially available magnets. Experimental results showed that a water droplet of approximately 0.3 mm diameter was levitated. The experimental space was nearly sealed and highly resistant to external disturbances, such as vibrations, allowing the water to remain in a non-contact levitated state unless the operator intentionally shook the experimental table or directed airflow to displace the water away. The device is expected to facilitate various applications in materials science and fluid dynamics as well as promote preliminary ground-based research on space-related experiments designed to be conducted in microgravity environments.