  Researchers seek methods to levitate matter for a wide variety of purposes,
ranging from exploring fundamental problems in science, through to developing
new sensors and mechanical actuators. Many levitation techniques require active
driving and most can only be applied to objects smaller than a few micrometers.
Diamagnetic levitation has the strong advantage of being the only form of
levitation which is passive, requiring no energy input, while also supporting
massive objects. Known diamagnetic materials which are electrical insulators
are only weakly diamagnetic, and require large magnetic field gradients to
levitate. Strong diamagnetic materials which are electrical conductors, such as
graphite, exhibit eddy damping, restricting motional freedom and reducing their
potential for sensing applications. In this work we describe a method to
engineer the eddy damping while retaining the force characteristics provided by
the diamagnetic material. We study, both experimentally and theoretically, the
motional damping of a magnetically levitated graphite plate in high vacuum and
demonstrate that one can control the eddy damping by patterning the plate with
through-slots which interrupt the eddy currents. We find we can control the
motional quality factor over a wide range with excellent agreement between the
experiment and numerical simulations.
