Title: Experimental Constraint on an Exotic Spin- and Velocity-Dependent Interaction in the Sub-meV Range of Axion Mass with a Spin-Exchange Relaxation-Free Magnetometer,
Abstract: We conducted a search for an exotic spin- and velocity-dependent interaction
for polarized electrons with an experimental approach based on a
high-sensitivity spin-exchange relaxation-free (SERF) magnetometer, which
serves as both a source of polarized electrons and a magnetic-field sensor. The
experiment aims to sensitively detect magnetic-fieldlike effects from the
exotic interaction between the polarized electrons in a SERF vapor cell and
unpolarized nucleons of a closely located solid-state mass. We report
experimental results on the interaction with 82 h of data averaging, which sets
an experimental limit on the coupling strength around $10^{-19}$ for the axion
mass $m_a \lesssim 10^{-3}$ eV, within the important axion window.