Nanomechanical detection of nuclear magnetic resonance using a silicon nanowire oscillator

The authors report the use of a radio frequency (rf) silicon nanowire mechanical oscillator as a low-temperature nuclear magnetic resonance force sensor to detect the statistical polarization of ${}^{1}\phantom{\rule{-0.16em}{0ex}}$H spins in polystyrene. To couple the ${}^{1}\phantom{\rule{-0.16em}{0ex}}$H spins to the nanowire oscillator, a magnetic resonance force detection protocol was developed that utilizes a nanoscale current\char21{}carrying wire to produce large time-dependent magnetic field gradients as well as the rf magnetic field. Under operating conditions, the nanowire experienced negligible surface-induced dissipation and exhibited an ultralow force noise near the thermal limit of the oscillator.