Magnetic Resonance Force Microscopy and Force-Detected NMR of Microcrystals

We report our advances in nuclear magentic resonance force microscopy (NMRFM) and NMR of microcrystals using force (mechanical oscillator) detection. For each, we report microfabrication of sensitive single-crystal-silicon multiple-torsional micro-oscillators using both optical and e-beam lithography and a back-etch technique. We characterize mechanical oscillator frequency, quality factor, and spring constant from the noise spectral density of oscillator motion, detected using fiber-optic interferometry. We review past work on scanning-mode detection of the NMR response from volumes as small as 2 $\mu$m$^3$ at room temperature. We primarily discuss progress in two experiments currently underway: 1) the study of $^1$H dynamics in submicron-thick metal hydride films, where the NMRFM technique permits selective response to motion-modulated dipolar interactions with correlation times from microseconds to seconds, and 2) detection of the $^{11}$B resonance in microcrystals over the temperature range $4\ {\rm K} < T < 300{\rm K}$. We also overview measurements made in our $^3$He low-temperature NMRFM system.