Electronic Band Structures and Physical Properties of Intercalation Compounds of Transition-Metal Dichalcogenides

过渡金属二硫化物插层化合物的电子能带结构和物理性质

基本信息

批准号：
61540235
负责人：
SUZUKI Naoshi
金额：
$ 0.77万
依托单位：
Osaka University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1986
资助国家：
日本
起止时间：
1986 至 1987
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-61540235/
关键词：
Transition-metal dichalcogenide Intercalation compounds Electronic band structure APW method Bond order Bonding state Antibonding state RKKY相互作用強磁性

项目摘要

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.

在APW能带计算的基础上，研究了M_xTiS_2（M=过渡金属）层间化合物的电子、结构和成键性质。还利用 2H-NbS_2 的真实能带结构研究了 M_xNbS_2 中的 RKKY 相互作用。主要结果如下： 1．非磁性M_xTis_2的电子能带和键合性质。(1)插层时，M-3d态在Ti-d<gamma>和S-p键合带与Ti-d非键合带之间形成新能带。费米能级位于这个新能带内。 Ti-d<gamma>和S-p组分在这个新能带中显着混合，其带宽相当大。(2)M-d<gamma>和S-p轨道也形成类共价键。 Ti 和 M 离子的 d 轨道显着杂化并形成键合和反键合状态。这些结果清楚地表明，所谓的刚性带模型不能应用于MxTiS_2，并且M-od电子应被视为流动电子。2．铁磁性Fe_<1/3>TiS_2和FeTiS_2的电子键。Fe 3d组分的上自旋能带和下自旋能带表现出较大的分裂，这不能描述为非磁性能带的刚性分裂。自旋矩在Fe_1/3TiS_2中被评估为2.55μ_B/晶胞，在FeTiS_2中被评估为3.22μ_B/晶胞。这一结果也表明了M 3d 电子的流动特性。3． M_xNbS_2 中的 RKKY 相互作用。M_xNbS_2 中 RKKY 相互作用引起的交换耦合是使用 2H-NbS_2 的实际能带结构在刚性带模型的基础上计算的。当x=1/4时，交换耦合的傅立叶变换在T点和K点处取几乎相同的极值，这表明铁磁或三角形自旋排列很可能实现。当x=1/3时，最稳定的自旋排列是Co^NbS_2中实现的M点对应的反铁磁结构。