Direct determination of Ti-3<i>d</i>¹ orbital state in YTiO₃ using synchrotron X-ray diffraction

The orbital degree of freedom of electrons greatly influences the physical properties of materials such as magnetism and unconventional superconductivity. An orbital is a minimal unit of “shape”, and the orbital state can be unraveled by observing the spatial anisotropic distribution of electrons. However, it is difficult to experimentally extract the orbital information in a crystal because of various technical problems. In this study, the Ti-3d orbital state in a perovskite-type oxide YTiO₃ is directly determined by a core differential Fourier synthesis (CDFS) method using synchrotron X-ray diffraction [1]. The valence electron density distribution, including information on the anisotropy and the hybridization between atomic orbitals, can be extracted from the CDFS analysis. Our study provides a non-trivial picture of the orbital state reconstructed by the orbital hybridization.

[1] S. Kitou et al., Phys. Rev. Research 2, 033503 (2020).