We theoretically address the quantum dynamics of a nanomechanical resonator
coupled to the macrospin of a magnetic nanoparticle by both instanton and
perturbative approaches. We demonstrate suppression of the tunneling between
opposite magnetizations by nanomechanical interference. By approximating the
macrospin as a two-level system, we describe magnetopolaritons and their
destruction by interference. The predictions can be verified experimentally by
a molecular magnet attached to a nanomechanical bridge.Comment: 4.4 pages, 3 figures. Slightly revised presentation, results
unchange