Abstract: Ultra-low-mass axions are a viable dark matter candidate and may form a coherently oscillating classical field. Nuclear spins in experiments on Earth might couple to this oscillating axion dark-matter field when propagating on Earth’s trajectory through our Galaxy. This spin coupling resembles an oscillating pseudo-magnetic field that modulates the spin precession of nuclear spins. 

In this talk, I will report on two recent results, obtained by analyzing data taken with the instrument which also produced the latest limit on the neutron electric dipole moment. The first result sets a limit on a spin-dependent interaction which could be mediated by an axion-like particle between the nucleons of bulk matter and ultra-cold neutrons. The second reports on a new limit obtained by analyzing the frequency modulation of freely precessing mercury-199 atoms.