Study on the electronic state near Fermi surface in dense Kondo alloys by measurement of optical absorption in for-infrared

本项目的最终目的是测量Kondo合金的红外光吸收，并分析与Kondo效应或重费米子系统有关的传导电子的动力学性质。要做到这一点，需要一些技术上的发展来估计光学常数及其与温度的关系。近藤效应在远红外传导电子的光学吸收中是如何出现的尚不清楚，因此对这一问题的研究是本课题的目的之一。本项目主要致力于稀近藤合金AUV的技术开发和分析，与致密的近藤合金相比，它是一种理想的例证物质，因为金是很好的参照物，而且近藤效应可以从光吸收对V浓度的依赖关系中区分出来。我们用量热法设计了一种更完善的低温恒温器，用来测量光吸收的绝对速率。为了分析AUV的光吸收，根据光吸收速率估计了光学常数，并与使用简单的Drude公式根据观测的直流电导计算的吸收进行了比较。结果表明，弛豫时间与频率有关，用共振散射模型可以很好地解释光谱分布。值得注意的是，共振能量比相当于近藤温度300K的能量小得多。

The final aim of this project is to measure the optical absorption infar-infrared for the Kondo alloys and to analyze the dynamical properties of the conduction electrons in relation to the kondo effect or the heavy Fermion system. To accomplish this, some technical developments are needed to estimate the optical constants and their dependence on temperature. How the Kondo effect appears in the optical absorption of the conduction electrons in far-infrared has not yet known, so investigation about that problem is one of aims of this project. The work in this project has been mainly devoted to the thechnical developments and and analysis on a dilute Kondo alloy AuV which is an ideal and illustrative substance in contrast with dense Kondo alloys, because Au is the good reference material, and the kondo effect can be separeted from the dependence of optical absorption on the concentration of V. We have constructed a more improved cryostat for meaurement of absolute rate of optical absorption by means of calorimetric method. For analysis of optical absorption of AuV, the optical constants were estimated from the rate of optical absorption, and were compared with the absorption calculated from observed dc-conductivity by using simple Drude formula. It was found that the relaxation time has frequency dependence,and that the spectrum profile can be well explanced by means of a resonant scattering model, It is noticeable that the resonant energy is considerabelly smaller than that equivalent to the Kondo temprature, 300K.