- 著者
- Arai Hideyuki Kudo Hiroshi Tomita Shigeo Ishii Satoshi
- 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.78, no.10, pp.104301, 2009-10
- 被引用文献数
- 5
We have specified the mechanism of suppressed electron emission from surfaces bombarded by fast cluster ions. From key information obtained from a comparison of the electron emissions for insulator KCl and conductor graphite, we concluded that the suppression is predominantly caused by the disturbance of the electron transport by the electric potential generated by moving cluster atoms. The possible shift from suppressed emission to enhanced emission of electrons as cluster speed increases is also discussed in relation to that in the case of cluster stopping power.
- 著者
- Suzuki Shugo Li Ming-Fang Ariizumi Toshihiro
- 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.77, no.7, pp.074703, 2008-07
- 被引用文献数
- 7 5
We study the structural, electronic, magnetic, optical, and magneto-optical properties of NpN in detail using the fully relativistic full-potential calculations based on the density functional theory within the local spin density approximation. We successfully reproduce the positive sign of the electric field gradient (EFG) at Np nuclei. The positive EFG is in striking contrast to the negative EFG in a Np3+ free ion, indicating the importance of the interplay between spin–orbit coupling and covalent bonding in NpN. Also, the calculated band structure shows large splittings induced by spin polarization and spin–orbit coupling, suggesting that both effects are indispensable for understanding the electronic properties of this material. This results in a large Kerr rotation angle of about 2°, which is comparable to those of uranium calcogenides.
- 著者
- Li Ming-Fang Ariizumi Toshihiro Suzuki Shugo
- 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.76, no.5, pp.054702, 2007-04
- 被引用文献数
- 10
We study the magneto-optical Kerr effect using fully relativistic calculations. Spin–orbit coupling is dealt with exactly solving the Dirac equation directly and the matrix elements of the Dirac matrices α are used in a fully relativistic expression of the Kubo formula for the optical conductivity derived with a relativistic sum rule. We also perform approximate calculations of the optical conductivity to examine the accuracy of a partly relativistic expression in which the matrix elements of the momentum operator p are used instead. As an example, we carry out calculations for bcc Fe and fcc Ni using the fully relativistic full-potential linear-combination-of-atomic-orbitals method. It is found that the partly relativistic treatment is good for the diagonal optical conductivity while it is not very good for the off-diagonal optical conductivity, the Kerr rotation angle, and the Kerr ellipticity. The results of the present study are compared to those of experimental and other theoretical studies.
- 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.