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

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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.