  We present a ground-state cooling scheme for the mechanical degrees of
freedom of mesoscopic magnetic particles levitated in low-frequency traps. Our
method makes use of a binary sensor and suitably shaped pulses to perform weak,
adaptive measurements on the position of the magnet. This allows us to
precisely determine the position and momentum of the particle, transforming the
initial high-entropy thermal state into a pure coherent state. The energy is
then extracted by shifting the trap center. By delegating the task of energy
extraction to a coherent displacement operation we overcome the limitations
associated with cooling schemes that rely on the dissipation of a two-level
system coupled to the oscillator. We numerically benchmark our protocol in
realistic experimental conditions, including heating rates and imperfect
readout fidelities, showing that it is well suited for magneto-gravitational
traps operating at cryogenic temperatures. Our results pave the way for
ground-state cooling of micron-scale particles.
