X-ray photon correlation spectroscopy study in valence fluctuation compound EuS

Nakao, Hironori*; Owada, Kenji; Shimomura, Susumu*; Ochiai, Akira*; Namikawa, Kazumichi*; Mizuki, Junichiro; Mimura, Hidekazu*; Yamauchi, Kazuto*; Murakami, Yoichi*

X-ray photon correlation spectroscopy (XPCS) is a powerful tool to perform direct measurements of the dynamics of fluctuations in condensed matter systems at atomic resolution. Here we have investigated spatial and time correlations of domains in the valence fluctuated phase in a typical valence fluctuation compound EuS near the charge ordering temperature (). The spatial correlation was observed at the fundamental reflection (4 4 4) using coherent diffraction techniques, which indicated that the domain size is longer than 200 nm near . The time correlation of the domain was measured by the XPCS technique, and we found that the slow fluctuation of the order of 10 second exists only near .