STUDY OF THE ELECTRONIC STRUCTURE OF STRONGLY CORRELATED ELECTRON SYSTEMS BY FAR-INFRARED AND MILLIMETER WAVES

在强关联电子系统中，CeNiSn和CeRhSbaar被认为是典型的近藤绝缘体，在费米能级附近有很小的能隙。为了进行这样的研究，需要对电子结构进行光谱研究。我们在低温下对这些材料进行了从毫米波到真空紫外区的非常宽的能区的反射测量。采用同步辐射作为光源。在本研究中，我们得到了以下结果：(1)通过反射测量，我们得到了CeNiSn和CeRhSb上精确的光学常数，以讨论光谱结构的起源。(2)从低温下对CeRhSb在远红外和毫米波区域的反射测量中，我们发现在3 meV以下的反射率明显降低，这可能与带隙的形成相对应。(3)在强磁场下利用超导磁体完整地构建了光谱系统，这使得测量强关联电子系统的透射率和反射率成为可能。

Among strongly correlated electron system, CeNiSn and CeRhSbare known as a typical Kondo insulator which has a very small energy gap near the Fermi energy level. For such investigation, spectroscopic study on the electronic structure is required to perform.We performed a reflection measurement on these materials at low temperature in the very wide energy region from a millimeter wave to a vacuum ultraviolet region. The synchrotron radiation was used as a light source. In this study, the following results were obtained,(1) From the reflection measurement, we obtained the exact optical constans on CeNiSn and CeRhSb to discuss the origin of the structure in the spectrum.(2) From the reflection measurement on CeRhSb in the far-infrared and millimeter wave regions at low temperature, we found the clear decrease in the reflectivity below 3meV which presumably corresponds to the gap formation.(3) The complete construction of the spectroscopic system under high magnetic field using a superconducting magnet which makes possible measurements of a transmission and a reflection on a strongly correlated electron system.