非定常点熱源加熱法による二次元異方性物質の主軸熱伝導率および主軸角の同時測定

抄録

In this paper we propose a new thermal conductivity measurement of a two-dimensional anisotropic heat conductor using an unsteady point source of heat. This method improves upon the principal thermal conductivity measurement of a steady point heat source and sink which was proposed by us in our previous report. This new method has two merits. First, it does not use a heat sink of the controlled cooling system. Second, it simplifies the calculation of two principal thermal conductivities and the principal rotating angle from the measured coordinates. To show the validity of this method, we have measured the two principal thermal conductivities and the principal rotating angle of the high-T_c superconductor Er₁Ba₂Cu₃O_7-y. The zero-resistance and onset temperature of this sample were 95.9K and 102K, respectively. In the superconductive transition range, both principal thermal conductivities had the peak values with decreasing temperature. Further, the principal rotating angle changed greatly from the normal conducting state to the superconductive state. The temperature dependences of the two thermal conductivities of this sample are similar to the Y₁Ba₂Cu₃O_7-y compound system which was reported in the results of our previous experiment.