Associate Professor, Graduate School of Frontier Sciences, The University of Tokyo
Development of photoemission and inverse-photoemission spectroscopy, electronic structure of transition-metal compounds
Photoelectrons are emitted from solid surfaces on which ultraviolet or x-ray light is shone. By measuring the energy and momentum of these photoelectrons, we can study occupied states of the solid (photoemission spectroscopy). On the other hand, we can study unoccupied states of the solid by detecting light emitted from surfaces of the solid on which electrons are shone (inverse-photoemission spectroscopy).
We are developing a high-energy-resolution inverse-photoemission system based on dispersion matching. Using photoemission and inverse-photoemission spectroscopy, we are studying the electronic structure of bulk and surface of various solids. In particular, we are interested in transition-metal compounds that show rich physical properties such as ferromagnetism, superconductivity, and metal-insulator transition. In transition-metal compounds, d-electrons with spin, charge and orbital degrees of freedom are affected by complicated lattice distortions, and display interesting electric and magnetic properties.
We are studying the relationship between the physical properties and electronic structure of transition-metal compounds using experimental methods such as photoemission and inverse-photoemission spectroscopy and theoretical methods such as model Hartree-Fock calculation. Here, an interesting question is which kind of electronic states are realized when d-electrons are confined at solid surface/interface. Another interesting question is how confined d-electrons behave when perturbed by photons. We are trying to answer these questions about d-electrons in various transition-metal compounds.
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| Fig. 1 |
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| Angle-resolved photoemission spectra of an insulating Cu-O chain due to charge ordering (left), a metallic Cu-O chain with Fermi liquid behavior (center), and a metallic Cu-O chain with Tomonaga-Luttinger liquid behavior (right). |
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| Fig. 2 |
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| Schematic drawing of high-energy resolution inverse-photoemission machine. The key idea is the dispersion matching between incoming electrons and outgoing light. |
Relevant papers
- Mizokawa, T., Kim, C., Shen, Z.-X., Ino, A., Yoshida, T., Fujimori, A., Goto, M., Eisaki, H., Uchida, S., Tagami, M., Yoshida, K., Rykov, A. I., Siohara, Y., Tomimoto, K., Tajima, S., Yamada, Yuh, Horii, S., Yamada, N., Yamada, Yasuji & Hirabayashi, I.
Angle-resolved photoemission study of insulating and metallic Cu-O chains in PrBa2Cu3O7 and PrBa2Cu4O8
Physical Review Letters 85, 4779 (2000). - Mizokawa, T., Tjeng, L. H., Sawatzky, G. A., Ghiringhelli, G., Tjengberg, O., Brookes, N. B., Fukazawa, H., Nakatsuji, S. & Maeno, Y.
Spin-orbit coupling in the Mott insulator Ca2RuO4
Physical Review Letters 87, 077202 (2001).. - Mizokawa, T., Nakada, K., Kim, C., Shen, Z.-X., Yoshida T., Fujimori, A., Horii, S., Yamada, Yuh, Ikuta, H. & Mizutani, U.
Preparation of Novel Silica-Cadmium Sulfide Composite Nanoparticles having Angle-resolved photoemission study of Zn-doped PrBa2Cu4O8 :Possible observation of single-particle spectral function for a Tomonaga-Luttinger liquid
Physical Review B 65, 193101, (2002).
