OPTICAL SPECTRUM OF STRONGLY CORRELATED ELECTRON SYSTEMS

强相关电子系统的光谱

• 批准号: 09440120
• 负责人: NANBA Takao
• 金额: $ 8.77万
• 依托单位: Kobe University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 1997
• 资助国家: 日本
• 起止时间: 1997 至 1998
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-09440120/
• 关键词: strongly correlated electron system; Infrared microscopic study; energy gap; TmTe; YbB_<12>; 赤外顕微鏡反射透過法

Infrared (IR) spectroscopic study is very useful method to investigate the electronic structure of materials with strong electron correlation because its has a very low photon energy and therefore it makes possible the low energy optical excitation in the solids. However, most of interesting materials grow in a very small single crystal-line state or in polycrystalline state with definite roughness. Therefore it is difficult to perform IR spectroscopic measurement with such specimens. In such a case, IR microscopic measurement seems to work well because, of microscope makes it possible to measure optical spectrum with a very tiny specimens. We performed reflection and transmission measurements on these materials by using IR microscope combined with IR interferometer (Bruker 66v) in the very wide energy region from far-infrared to ultraviolet.In this study, the following results were obtained,(1) From the transmission measurement on TmTe and SmTe which are both a semiconductor with a small energy gap in the IR region, we found that TmTe has a characteristic absorption structure at 150meV in the absorption edge. On the other hand, SmTe showed a simple absorption edge. The electronic structure close to the fermi level are different from each other althpough the electron configuration of both materials are very similar.(2) YbB_<12> is recognized as a typical Kondo-insulator which exhibits a formation of small energy gap only at low temperature. From the reflection measurement with an accuracy within 1% in the reflectivity on Yb_<1-x>Lu_xB_<12> single crystal, we foud that the gradual substitution of non-magnetic Lu with Yb gives rise to an appearance of a new band in the band gap in YbB_<12> at low temperature.(3) IR microscopic measurement was confirmed to be very effective in the study of the electronic structure of strongly correlated electron systems.

红外（IR）光谱研究是研究强电子关联材料的电子结构的非常有用的方法，因为它具有非常低的光子能量，因此它使得固体中的低能光激发成为可能。然而，大多数有趣的材料都以非常小的单晶态或多晶态生长，具有一定的粗糙度。因此，很难对此类样品进行红外光谱测量。在这种情况下，红外显微测量似乎效果很好，因为显微镜可以用非常小的样本测量光谱。我们利用红外显微镜结合红外干涉仪（Bruker 66v）在从远红外到紫外的非常宽的能量区域对这些材料进行了反射和透射测量。在这项研究中，得到了以下结果：（1）通过对TmTe和SmTe这两种在红外区域能隙较小的半导体的透射测量，我们发现TmTe在150meV处具有特征吸收结构 在吸收边。另一方面，SmTe 显示出简单的吸收边。尽管两种材料的电子构型非常相似，但接近费米能级的电子结构彼此不同。(2)YbB_<12>被认为是典型的近藤绝缘体，仅在低温下才表现出小能隙的形成。通过对Yb_<1-x>Lu_xB_<12>单晶反射率精度在1%以内的反射测量，我们发现Yb逐渐取代非磁性Lu，在低温下YbB_<12>带隙中出现了新的能带。(3)红外显微测量被证实对于强强电子结构的研究非常有效。 相关电子系统。

项目成果

Hidekazu Okamura: "Optical conductivity of the Kondo insulator YbB12:Gap formation and low-energy excitation" Physical Review. B58(12). R7496-R7499 (1998)

Hidekazu Okamura：“近藤绝缘体 YbB12 的光导率：间​​隙形成和低能激发”物理评论。

Takao Nanba: "High-pressure solid state spectroscopy atUVSOR by Infrared Synchrotron Radiation" IL NUOVO CIMENTO, 16 (1998)

Takao Nanb​​a：“通过红外同步辐射进行 UVSOR 的高压固态光谱” IL NUOVO CIMENTO，16 (1998)

HIDEKAZU OKAMURA: "Optical conductivity of the Kondo insulator YbB12 : Gap formation and low-energy excitation" Physical Review. B58 (12). R7496-R7499 (1998)

HIDEKAZU OKAMURA：“近藤绝缘体 YbB12 的光导率：间​​隙形成和低能激发”物理评论。

TAKAO NANBA: "High-pressure solid state spectroscopy at UVSOR by Infrared Synchrotron Radiation" IL NUOVO CIMENTO. 20 (4). 397-413 (1998)

TAKAO NANBA：“红外同步辐射 UVSOR 高压固态光谱”IL NUOVO CIMENTO。