| Project/Area Number |
61540235
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
固体物性
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| Research Institution | Osaka University |
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Principal Investigator |
SUZUKI Naoshi Faculty of Engineering Science, Osaka University, 基礎工学部, 助教授 (40029559)
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| Co-Investigator(Kenkyū-buntansha) |
MOTIZUKI Kazuko Faculty of Engineering Science, Osaka University, 基礎工学部, 教授 (90029413)
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| Project Period (FY) |
1986 – 1987
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| Project Status |
Completed (Fiscal Year 1987)
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| Budget Amount *help |
¥1,200,000 (Direct Cost: ¥1,200,000)
Fiscal Year 1987: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1986: ¥700,000 (Direct Cost: ¥700,000)
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| Keywords | Transition-metal dichalcogenide / Intercalation compounds / Electronic band structure / APW method / Bond order / Bonding state / Antibonding state / RKKY相互作用 / 強磁性 |
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| Research Abstract |
Electronic and structures and bonding natures of intercalation compounds of M_xTiS_2 (M=transition metal) are studied on the basis of tne APW band calcuation. RKKY interaction in M_xNbS_2 is also studied by using the realistic band structures of 2H-NbS_2. The main results are summarized as follows.
1. Electronic bands and bonding natures of non-magnetic M_xTis_2.
(1) On intercalation the M-3d states form a new bands between the Ti-d<gamma> and S-p bonding band and the Ti-d non-bonding band. The Fermi level lies in this new band. The Ti-d<gamma> and S-p components are mixed significantly in this new band and its band width is fairly large.
(2) The M-d<gamma> and S-p orbitals make also covalent-like bonds. The d orbitals of Ti and M ions hybridise significantly and form also bonding and anti-bonding states. These results suggest clearly that the so-called rigid-band-model cannot be applied for MxTiS_2 and that the M-od electrons should be treated as itinerant electrons.
2. Electronic bonds of ferromagnetic Fe_<1/3>TiS_2 and FeTiS_2.
Up- and down-spin bands of Fe 3d components show a large splitting, shich cannot be described as a rigid splitting of the non-magnetic bands. The spin moment is evaluated as 2.55<mu>_B/unit cell in Fe_<1/3>TiS_2 and 3.22<mu>_B/unit cell in FeTiS_2. This result indicate also itinerant character of the M 3d electrons.
3. RKKY interaction in M_xNbS_2.
Exchange couplings due to RKKY interaction in M_xNbS_2 are calculated on the basis of the rigid-band-model by using the realistic band structures of 2H-NbS_2. When x=1/4, Fourier transform of the exchange couplings takes the almost same extremum at the T and K points, which indicate either ferromagnetic or triangular spin arrangement is likely to be realsized. When x=1/3, the most stable spin arrangement is the antiferromagnetic structure corresponding to the M point which is realized in Co^</3>NbS_2.
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