Nature Nanotech. http://doi.org/kg7 (2013)

Magnetism is often thought of as a bulk property, but isolated molecules can also have a non-zero magnetic moment. Application of these single-molecule magnets (SMMs) often requires that the spin state remains stable for a prolonged time. However, vibrations can switch the magnet between different states. Marc Ganzhorn and colleagues have now shown how nanomechanical resonators can help.

A spin state cannot relax unless a phonon of commensurate energy is available. The key then is to control the vibrations. The continuous energy range of vibrations in three-dimensional materials makes this impossible. One-dimensional materials, however, only support phonons with a discrete set of energies.

Ganzhorn et al. grafted an SMM known as TbPc2 to a suspended carbon nanotube. They demonstrate strong coupling between the two by showing that a longitudinal phonon mode of the nanotube is activated whenever the spin of the magnet flips direction. This system could be used as a probe of magnetic fields, or even as a quantum bit.