- 著者
- Suzuki Shugo Hirosawa Jin Nakao Kenji
- 出版者
- The Physical Society of Japan
- 雑誌
- Journal of the Physical Society of Japan (ISSN:00319015)
- 巻号頁・発行日
- vol.75, no.8, pp.084709, 2006-08
We study low-energy excitations in the Mott–Jahn–Teller insulator A4C60 theoretically, where A is alkali metal. A model which takes account of both the electron–electron and electron–phonon interactions is employed and the low-energy excitations are calculated by using the Tamm–Dancoff approximation. It is found that the lowest excitation corresponds to the creation of the spin-singlet Frenkel excitons at about 0.3 eV and the next lowest excitation corresponds to the creation of the spin-triplet Frenkel excitons at about 0.6 eV. It is also found that the excitations of a pair of a free electron and a free hole lie over 0.8 eV. A remarkable point is that the spin-singlet Frenkel excitons are lower in energy than the spin-triplet Frenkel excitons in A4C60 in contrast to usual insulators.