Paper detail

Magnetic and electric dipole moments of the $H\ {}^3Δ_1$ state in ThO

The metastable $H \ {}^3Δ_1$ state in the thorium monoxide (ThO) molecule is highly sensitive to the presence of a CP-violating permanent electric dipole moment of the electron (eEDM). The magnetic dipole moment $μ_H$ and the molecule-fixed electric dipole moment $D_H$ of this state are measured in preparation for a search for the eEDM. The small magnetic moment $μ_H = 8.5(5) \times 10^{-3} \ μ_B$ displays the predicted cancellation of spin and orbital contributions in a ${}^3 Δ_1$ paramagnetic molecular state, providing a significant advantage for the suppression of magnetic field noise and related systematic effects in the eEDM search. In addition, the induced electric dipole moment is shown to be fully saturated in very modest electric fields ($<$ 10 V/cm). This feature is favorable for the suppression of many other potential systematic errors in the ThO eEDM search experiment.