| Project/Area Number |
18540324
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Condensed matter physics I
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| Research Institution | Kure National College of Technology |
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Principal Investigator |
KOYAMA Michie Kure National College of Technology, Department of General Edcation, professor (10099848)
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| Co-Investigator(Kenkyū-buntansha) |
UEDA Yoshifumi Kure College of Technology, Department of Electrical Engineering and Information Science, professor (10127615)
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| Project Period (FY) |
2006 – 2007
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| Project Status |
Completed (Fiscal Year 2007)
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| Budget Amount *help |
¥3,710,000 (Direct Cost: ¥3,500,000、Indirect Cost: ¥210,000)
Fiscal Year 2007: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000)
Fiscal Year 2006: ¥2,800,000 (Direct Cost: ¥2,800,000)
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| Keywords | choromium chakogenide / Phase transition / magnetism / resonant photoemission snectroscopy / resonant inverse photoemission snectroscopy / electronic structure / partial density of state / 共鳴逆光電子分光 / 光電子分光 / 逆光電子分光 / 電子状態密度 |
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| Research Abstract |
It is known that the physical properties of chromium chalcogenides depend on the ratio of composition. Cr_xY (Y=S, Se, Te) show the phase transition at transition point. The metal-semiconductor phase transition is observed for CrS and CrSe at transition point. Physical properties are related with electronic structures near Fermi level E_F. The electronic band-structures of CrS, CrSe and Cr_xTe are reported. In this study, we present the electronic structures in these series of chromium chalcogenides. The density of states (DOSs) are compared and discussed from the view points of the effect of the vacancies at Cr sites and chalcogen species on electronic structures. These DOSs are also compared with the result of the band-structure calculation.
We obtained the conduction-band and the unoccupied Cr 3d partial DOSs by resonant inverse photoemission measurements at the Cr 3p-3d excitation region. It can be concluded that the Cr 3d pDOS of CrS (x=1), Cr_xSe and Cr_xTe are almost independent on the vacancies at Cr sites, as similar as those of the valence-band. The Cr 3d exchange splitting energy becomes lager as chalcogen changes from S to Se and further to Te. This tendency is similar to the calculated exchange splitting energies. However, the measured exchange splitting energies are larger than those of calculation.
The metal-semiconductor transition is observed in CrS. Therefore, we measured the electronic structure of CrS near EF at low temperatures, with high-resolution and low-temperature photoemission spectrometers. The intensity of photoemission spectra near EF becomes lower as the temperature decreases. A structural change was observed according to the measurement temperature.
In CrS, x-dependence on the electronic structures are now also planning to measure the RIPES. In order to study Cr substitutional effect with 3d transition metal ions on the electronic structures, samples of (CrxVi_x)_3Te_4 have been grown, and now are ready to measure DOSs.
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