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

The axion is a promising dark matter candidate, which was originally proposed to solve the strong-CP 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) less than or similar to 1 mu eV. ABRACADABRA is a new experimental program to search for axion dark matter over a broad range of masses, 10(-12) less than or similar to m(a) less than or similar to 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 gamma gamma) < 1.4 x 10(-10) and g(a gamma gamma) < 3.3 x 10(-9) GeV-1 over the mass range 3.1 x 10(-10)-8.3 x 10(-9) eV. These results are competitive with the most stringent astrophysical constraints in this mass range.