Study on the metal-insulator transition of Ti oxide single crystals caused from the band filling by means of photoemission and inverse-photoemission spectroscopies

利用光电发射光谱和反光电发射光谱研究Ti氧化物单晶因带填充引起的金属-绝缘体转变

基本信息

批准号：
15540313
负责人：
SATO Hitoshi
金额：
$ 1.6万
依托单位：
HIROSHIMA UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2003
资助国家：
日本
起止时间：
2003 至 2004
项目状态：
已结题

项目摘要

Distorted perovskite-type Y_<1-x>Ca_xTiO_3 is a system which moves from the Mott insulator YTiO_3(x=0) to the band insulator CaTiO_3(x=1) across the metallic phase, by controlling the Ti 3d band filling with x. In particular, Y_<1-x>Ca_xTiO_3 with x=0.39 exhibits a sharp metal-insulator transition (MIT) around 150 K (high-temperature phase : insulator, low-temperature phase : metal).We have carried out for x=0.39 the Ti 3p-3d resonant photoemission and inverse-photoemission spectroscopies (PES abd IPES) and observed the occupied and unoccupied Ti 3d densities of states, that is, the remnant of the lower and upper Hubbard bands split by the electron correlation. The experimental results revealed that the U_<eff>-value, determined from their energy separation, increases with decreasing temperature. Since the Coulomb interaction energy of the bare Ti 3d electrons is considered to be almost intraatomic value, the U_<eff> reduction reflects that the Ti 3d bands become wider at low temperature.In order to analyze the IPES spectra of x=0.39, we have measured the O 1s soft x-ray absorption spectra in comparison with the IPES spectra. The subtle structure, possibly corresponding to the coherent part in the PES spectra, seems to appear in the lower energy side of the unoccupied Ti 3d structure. This component is considered to be closely related to MIT. We have to reconfirm the existence by the IPES with higher energy resolution.We have also PES for x=0.39 using hard x-ray (several keV), which is more bulk-sensitive. The lower Hubbard band shifts to the shallower binding-energy side compared with the PES spectra with several ten eV. This suggests that the correlation effect is strong near the surface. In addition, for the metallic phase, a new component has been found in the Ti 2p PES, probably being attributed to the well screened state as observed in the Mn 2p PES of La_<1-x>Sr_xMnO_3 in the metallic phase [1].[1]K.Horiba et al., Phys.Rev.Lett. 93,236401 (2004).

扭曲的perovskite-type y_ <1-x> ca_xtio_3是一个系统，它从莫特绝缘体ytio_3（x = 0）移动到整个金属阶段的频带绝缘器catio_3（x = 1），通过用x填充Ti 3D频段。 In particular, Y_<1-x>Ca_xTiO_3 with x=0.39 exhibits a sharp metal-insulator transition (MIT) around 150 K (high-temperature phase : insulator, low-temperature phase : metal).We have carried out for x=0.39 the Ti 3p-3d resonant photoemission and inverse-photoemission spectroscopies (PES abd IPES) and observed the occupied and未占用状态的未占用Ti 3D密度，即由电子相关性分裂的下部哈伯德带的残余。实验结果表明，U_ <fef> - 值是根据其能量分离确定的，随温度降低而增加。由于裸露Ti 3D电子的库仑相互作用能被认为几乎是原子质值，因此U_ <ff>还原反映出Ti 3D频段在低温下在低温下变得更宽。微妙的结构可能与PES光谱中的相干部分相对应，似乎出现在未居住的Ti 3D结构的较低能量侧。该组件被认为与MIT密切相关。我们必须通过使用硬X射线（几个KEV）的IPE重新确认IPE具有较高能量分辨率的IPE的存在，X = 0.39（几个KEV），这更浓郁。与PES光谱相比，下部的哈伯德带移到了较浅的结合 - 能源侧。这表明相关效应在表面附近很强。此外，对于金属阶段，在Ti 2p PES中发现了一个新组件，可能归因于筛选的状态，如La_ <1-X> sr_xmno_3在金属相[1]中的Mn 2p PES [1]。[1] K.Horiba等人。 93,236401（2004）。

项目成果

期刊论文数量（40）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

Hole-doping and pressure effects on the metal-insulator transition in single crystals of Y_<1-x>Ca_xTiO_3 (0.37【less than or equal】x【less than or equal】0.41)

空穴掺杂和压力对Y_<1-x>Ca_xTiO_3单晶金属-绝缘体转变的影响（0.37【小于等于】x【小于等于】0.41）

DOI：
发表时间：
2003
期刊：
Journal of the Physical Society of Japan 72・12
影响因子：
0
作者：
K.Umemori;M.Izawa;K.Saito;S.Sakanaka;F.Iga et al.;H.Sato et al.;H.Matsuhata et al.;H.Sato et al.;F.Iga他12名;H.Sato他19名;H.Matsuhata他6名;H.Sato他10名;M.Tsubota 他13名
通讯作者：
M.Tsubota 他13名

M Tsubota et al.: "Hole-doping and pressure effects on the metal-insulator transition in single crystals of Y_<1-x>Ca_xTiO_3 (0.37<x<0.41)"Journal of the Physical Society of Japan. 72・12. 3182-3188 (2003)

M Tsubota 等：“Y_<1-x>Ca_xTiO_3 (0.37<x<0.41) 单晶中的空穴掺杂和压力效应”日本物理学会杂志 72・12。 3182-3188 (2003)

DOI：
发表时间：
期刊：
影响因子：
0
作者：
通讯作者：

Phase separation in Y_<1-x>Ca_xTiO_3 associated with the insulator to metal transition

Y_<1-x>Ca_xTiO_3 中的相分离与绝缘体到金属的转变有关

DOI：
发表时间：
2004
期刊：
Physical Review B 70・13
影响因子：
0
作者：
K.Umemori;M.Izawa;K.Saito;S.Sakanaka;H.Sato 他19名;H.Matsuhata 他6名
通讯作者：
H.Matsuhata 他6名

Valence transition of YbInCu_4 observed in hard x-ray photoemission spectra

硬X射线光电子能谱观察到的YbInCu_4的价态跃迁

DOI：
发表时间：
2004
期刊：
Physical Review Letters 93・24
影响因子：
0
作者：
K.Umemori;M.Izawa;K.Saito;S.Sakanaka;H.Sato 他19名
通讯作者：
H.Sato 他19名

Electronic structure of oxysulfide (LaO)CuS and (La_<1-x>Ca_xO)Cu_<1-x>Ni_xS (x【less than or equal】0.10) studied by PES and IPES

PES和IPES研究氧硫化物(LaO)CuS和(La_<1-x>Ca_xO)Cu_<1-x>Ni_xS (x【小于等于】0.10)的电子结构

DOI：
发表时间：
2003
期刊：
Physical Review B 68・3
影响因子：
0
作者：
K.Umemori;M.Izawa;K.Saito;S.Sakanaka;F.Iga et al.;H.Sato et al.;H.Matsuhata et al.;H.Sato et al.;F.Iga他12名;H.Sato他19名;H.Matsuhata他6名;H.Sato他10名;M.Tsubota 他13名;H.Sato 他12名
通讯作者：
H.Sato 他12名