First Results from ABRACADABRA-10 cm: A Search for Sub-μ eV Axion Dark Matter

The axion is a promising dark matter candidate, which was originally proposed to solve the strong-C P problem in particle physics. To date, the available parameter space for axion and axionlike particle dark matter is relatively unexplored, particularly at masses m_a≲1 μ eV . ABRACADABRA is a new experimental program to search for axion dark matter over a broad range of masses, 10^-12≲m_a≲10^-6 eV . ABRACADABRA-10 cm is a small-scale prototype for a future detector that could be sensitive to the QCD axion. In this Letter, we present the first results from a 1 month search for axions with ABRACADABRA-10 cm. We find no evidence for axionlike cosmic dark matter and set 95% C.L. upper limits on the axion-photon coupling between g_{a γ γ}<1.4 ×10^-10 and g_{a γ γ}<3.3 ×10^-9 GeV^-1 over the mass range 3.1 ×10^-10- 8.3 ×10^-9 eV . These results are competitive with the most stringent astrophysical constraints in this mass range.