Thermopower of RBa_2 Cu_3 O_(7-y) for R=Yb, Er, Dy, and Gd = RBa_2Cu_3O_(7-y)(R=Yb, Er, Dy, Gd)의 열기전력 측정연구

다국어 초록 (Multilingual Abstract)

We have measured the thermopower of RBa_2Cu_3O_(7-x), for R=Yb, Er, Dy, and Gd. We find that the thermopower is sensitive to the 3+ ion radius of the rare earth element in the material. For YbBa_2Cu_3O_(7-y), which has the rare earth element of the smallest ion-radius, the thermopower is negative unlike others. We also find that the thermopower vs. temperature curves are all similar in shape for every 1 : 2 : 3 compound, regardless of the sign of thermopower, charge carrier concentration and the rare earth element in the materials. As a plausible explanation for the experimental results, a two-band model is considered.
Ever since the discovery of the new high-Tc superconductors, the electronic structure of the materials has been intensively studied. Despite a great deal of efforts, the electronic band structure, knowledge of which is essential to understand the superconducting mechanism in the materials, is not known in detail. In such a situation, the thermopower of the materials draws particular attention since it sensitively reflects the underlying electronic structural configuration. Measurements on selected high-Tc
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