Eur. Phys. J. B 47, 3–27 (2005) DOI: 10.1140/epjb/e2005-00303-4
THE EUROPEAN PHYSICAL JOURNAL B
Resonant inelastic X-ray scattering in d and f electron systems
A. Kotania
RIKEN Harima Institute, 1-1-1 Kouto, Mikazuki-cho, Sayo-gun, Hyogo, 679-5148, Japan and Photon Factory, Institute of Materials Structure Science, 1-1 Oho, Tsukuba, Ibaraki 305-0801, Japan Received 10 February 2005 Published online 21 September 2005 – c EDP Sciences, Societ` Italiana di Fisica, Springer-Verlag 2005 a Abstract. Recent progress in the study of resonant inelastic X-ray scattering (RIXS) spectroscopy in d and f electron systems is described. The main space is devoted to the theoretical investigations, some typical experimental data and the comparison of calculated and experimental results, putting emphasis on the underlying physical mechanisms. We conne ourselves mainly to the studies performed since 2000, and discuss the following topics: (1) RIXS in high Tc cuprates, (2) f 0 and d0 systems, (3) other transition metal compounds, (4) RIXS by electric quadrupole excitation, and (5) magnetic circular dichroism in RIXS of ferromagnetic systems. Some brief description is also given on the future prospect of the RIXS study. PACS. 78.70.Ck X-ray scattering – 78.70.Dm X-ray absorption spectra – 78.70.En X-ray emission spectra and uorescence – 71.27.+a Strongly correlated electron systems; heavy fermions
1 Introduction
Resonant inelastic X-ray scattering (RIXS) is a powerful probe of electronic excitations in condensed matter systems. In RIXS, a core electron is excited, by the incident X-ray, near to the absorption threshold, and then the excited state decays by emitting an X-ray photon. Therefore, RIXS is a second order optical process in contrast to that X-ray photoemission spectroscopy (XPS) and X-ray absorption spectroscopy (XAS) are rst order optical processes. The intensity of the signal in RIXS is much weaker than XPS and XAS, because the eciency of the X-ray emission is quite low, so that high-brilliance X-ray sources are required to obtain precise RIXS experimental data. The recent development in the RIXS study owes to the utilization of the third generation synchrotron radiation as an extremely high-brilliance X-ray source [1–3]. Since RIXS includes the information of both X-ray excitation and X-ray emission inherent in the second order optical process, the information obtained from RIXS is greater than that obtained from the rst order optical processes XPS and XAS. Furthermore, RIXS provides us with bulk-sensitive and site-selective information, and the technique of RIXS can be applied equally to metals and insulators. RIXS can be performed in applied electric or magnetic elds, as well as under high pressure, since it is a photon-in and photon-out process [1–3]. Let us consider the RIXS process where an X-ray photon with energy (wave vector k1 ) and polarization λ1 (polarization vector ek1 λ1 ) is incident on a material and

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