Spin-mediated photomechanical coupling of a nanoelectromechanical shuttle

We show that nano-mechanical vibrations in a magnetic shuttle device can be strongly affected by external microwave irradiation through photo-assisted electronic spin-flip transitions. Mechanical consequences of these spin-flips are due to a spin-dependent magnetic force, which may lead to a nano-mechanical instability in the device. We derive a criterion for the instability to actually occur and analyze different regimes of possible nano-mechanical oscillations. Possible experimental realizations of the spin-mediated photo-mechanical instability and detection of the device back action are discussed.