Fig. 1: Overview of the pump-induced dynamics and the information the X-ray absorption probe can provide.

a Excitation of an electron from the \({d}_{{z}^{2}}\) to \({d}_{{x}^{2}-{y}^{2}}\) changes the JT distortion from axial elongation to axial compression. Bottom: in the electronic ground state, the magneto-crystalline anisotropy is easy axis type where the spin magnetic moment aligns along the anisotropy axis. Therefore, the lowest energy configuration occurs when the z-component of the spin quantum number \({M}_{s}=\,\pm S\). After excitation and the JT switch, the complex exhibits easy plane anisotropy and the spin magnetic moment preferentially aligns in the plane perpendicular to the anisotropy axis with the lowest energy state \({M}_{s}=\,0\). b Basic schematic of the experiment. A pump laser excites the sample (Mn₃) and an intense X-ray beam is used to measure the K-edge spectra of the sample before and after excitation using total fluorescence detection. The intensity of the spectra is given by the total fluorescence yield. The peripheral atoms of the Mn₃ have been removed for clarity. Mn, pink; O, red; N, blue. c K-edge spectrum and transitions associated with the spectral features.