Coherent spin dynamics in gadolinium-doped CaWO4 crystal

We report the first observation of Rabi oscillations in the spin-7/2 ensemble of trivalent gadolinium ions hosted in CaWO4 single crystal. A number of transitions within the lowest electronic multiplet 8S7/2 of Gd3+ ion are studied using a combination of continuous-wave and pulsed electron paramagnetic resonance spectroscopy. The corresponding Rabi damping curves and the spin coherence times are detected at varying strengths of the microwave field. These data are well reproduced by a theoretical model which accounts for the inhomogeneity of the microwave field within the crystal sample volume and the magnetic dipole interactions in the diluted spin ensemble.