  We propose a technique for sensitive magnetic point force detection using a
suspended carbon nanotube (CNT) mechanical resonator combined with a magnetic
field gradient generated by a ferromagnetic gate electrode. Numerical
calculations of the mechanical resonance frequency show that single Bohr
magneton changes in the magnetic state of an individual magnetic molecule
grafted to the CNT can translate to detectable frequency shifts, on the order
of a few kHz. The dependences of the resonator response to device parameters
such as length, tension, CNT diameter, and gate voltage are explored and
optimal operating conditions are identified. A signal-to-noise analysis shows
that in principle, magnetic switching at the level of a single Bohr magneton
can be read out in a single shot on timescales as short as 10 microseconds.
This force sensor should enable new studies of spin dynamics in isolated single
molecule magnets, free from the crystalline or ensemble settings typically
studied.
