Study of photoinduced valence dynamics in EuNi${}_2$(Si${}_{0.21}$Ge${}_{0.79}$)${}_2$ through time-resolved X-ray absorption spectroscopy

Abstract

The photoinduced valence dynamics of EuNi${}_2$(Si${}_{0.21}$Ge${}_{0.79}$)${}_2$ are investigated using time-resolved X-ray absorption spectroscopy for Eu $M_5$-edge. Through the pump-probe technique with synchrotron X-ray and Ti:sapphire laser pulse, a photoinduced valence transition is observed from Eu${}^{3+}$ to Eu${}^{2+}$. Because the lifetime of a photoinduced state can be up to 3 ns, a metastable state is considered to be realized. By comparing the experimental results with the theoretical calculations, the photoinduced valence transition between Eu 4$f$ and conduction electrons is quantitatively evaluated.

5 pages, 5 figures