****

Transition-metal oxides have energetically degenerate d orbitals, which often yield the freedom of which to occupy by electrons, called "orbital degree of freedom".
Here, how light interacts with the transition-metal oxides having such orbital degree of freedom is closely related to the excited states of the orbital degree of freedom.
In this research project, we perform both "the development of materials suitable to measurement" and "optical measurement of the materials" to clarify this orbital-photon interaction for transition-metal oxides.