Calibration of the Solid‐State Nuclear Magnetic Resonance Search for Axion‐Like Dark Matter.

Calibration of nuclear‐magnetic‐resonance‐based searches for axion‐like dark matter can be performed by free induction decay (FID) measurements. This manu‐ script describes FID experiments on several solid materials, motivated by the Cosmic Axion Spin Precession Experiment (CASPEr) program. Experiments with207Pb nuclear spins in ferroelectrics, lead magnesium niobate‐lead titanate (PbMg1/3Nb2/3O3)2/3−${}_{2/3}-$ (PbTiO3)1/3 (PMN‐PT) and lead zirconium titante PbZr0.52Ti0.48O3 (PZT) are directly relevant to the CASPEr‐electric search for the electric dipole moment interaction of axion‐like dark matter. Experiments with 31P nuclear spins in gadolinium‐doped hydroxypyromorphite Pb4.95Gd0.05(PO4)3OH (HPM:Gd) are used for apparatus calibration. The measurements characterized the nuclear spin ensemble coherence time and the magnetic resonance detection sensitivity for these samples. Calibration is performed using small tip‐angle pulses. [ABSTRACT FROM AUTHOR]