Real‐Space Observation of Ligand Hole State in Cubic Perovskite SrFeO<sub>3</sub>
Shunsuke Kitou, Masaki Gen, Yuiga Nakamura, Kunihisa Sugimoto, Y. Tokunaga, Shintaro Ishiwata, and Taka‐hisa Arima
Abstract
Abstract An anomalously high valence state sometimes shows up in transition‐metal oxide compounds. In such systems, holes tend to occupy mainly the ligand p orbitals, giving rise to interesting physical properties such as superconductivity in cuprates and rich magnetic phases in ferrates. However, no one has ever observed the distribution of ligand holes in real space. Here, a successful observation of the spatial distribution of valence electrons in cubic perovskite SrFeO 3 by high‐energy X‐ray diffraction experiments and precise electron density analysis using a core differential Fourier synthesis method is reported. A real‐space picture of ligand holes formed by the orbital hybridization of Fe 3 d and O 2 p is revealed. The anomalous valence state in Fe is attributed to the considerable contribution of the ligand hole, which is related to the metallic nature and the absence of Jahn‐Teller distortions in this system.