We describe a method based on precision magnetometry that can extend the search for axion-mediated spin-dependent forces by several orders of magnitude. By combining techniques used in nuclear magnetic resonance and short-distance tests of gravity, our approach can substantially improve upon current experimental limits set by astrophysics, and probe deep into the theoretically interesting regime for the Peccei-Quinn (PQ) axion. Our method is sensitive to PQ axion decay constants between ${10}^9$ and ${10}^{12}\mathrm{GeV}$ or axion masses between ${10}^{-6}$ and ${10}^{-3}\mathrm{eV}$, independent of the cosmic axion abundance.

• Received 5 March 2014

DOI:https://doi.org/10.1103/PhysRevLett.113.161801