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arXiv · 1809.09351

Feasibility of imaging using Boltzmann polarization in nuclear Magnetic Resonance Force Microscopy

Martin de Wit·Gesa Welker·Jelmer Wagenaar·Freek Hoekstra·Tjerk Oosterkamp
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Abstract

We report on Magnetic Resonance Force Microscopy measurements of the Boltzmann polarization of the nuclear spins in copper by detecting the frequency shift of a soft cantilever. We use the time-dependent solution of the Bloch equations to derive a concise equation describing the effect of rf magnetic fields on both on- and off-resonant spins in high magnetic field gradients. We then apply this theory to saturation experiments performed on a 100 nm thick layer of copper, where we use the higher modes of the cantilever as source of the rf field. We demonstrate a detection volume sensitivity of only (40 nm)$^3$, corresponding to about 1.6$\cdot 10^4$ polarized copper nuclear spins. We propose an experiment on protons where, with the appropriate technical improvements, frequency-shift based magnetic resonance imaging with a resolution better than (10 nm)$^3$ could be possible. Achieving this resolution would make imaging based on the Boltzmann polarization competitive with the more traditional stochastic spin-fluctuation based imaging, with the possibility to work at milliKelvin temperatures.

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Martin de Wit, Gesa Welker, Jelmer Wagenaar, Freek Hoekstra, Tjerk Oosterkamp. 2018-09-25. Feasibility of imaging using Boltzmann polarization in nuclear Magnetic Resonance Force Microscopy. https://doi.org/10.1063/1.5064449

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