Fig. 3: Electron-nuclear spin coherence rotation demonstrated by HYSCORE technique in for Cr³⁺ centers in Cs₂NaInCl₆ host.

A Pulse sequence for a HYSCORE experiment: \(\pi /2\to \tau \to \pi /2\to T1\to \pi \to T2\to \pi /2\to \tau \to\) echo. Here the second \(\pi /2\) after a time delay \(\tau\) partially converses electron spin coherence into polarization. This also encodes electron spin coherence to nuclear coherence under the hyperfine interaction. The \(\pi\) pulse transfers spin polarization between two Zeeman sublevels, causing a relative change of the correlated nuclear spin rotation, the final \(\pi /2\) transfers the electron spin polarization back to electron spin coherence, causing the stimulated echo to happen at the time \(\tau\). B HYSCORE coherence spectrograph of the Cr[Na] samples at 4 K, mapped in two dimensions as a function of T1 and T2. C Frequency domain plot of the HYSCORE data. D Nuclear frequency analysis, including the contribution of S = 3/2 Cr³⁺ interacting with both ¹³³Cs (I = 7/2) and ^35,37Cl (I = 3/2) nuclear spins.