Microwave characteristics of high-T_c superconductors by improved three-fluid model

• IMAI T.

  Faculty of Engineering, Saitama University

• Sakakibara Takaaki

  Faculty of Engineering, Saitama University

• Kobayashi Yoshio

  Faculty of Engineering, Saitama University

抄録

In order to explain the temperature and frequency characteristics of high-T_c superconductors, a new model is proposed, which will be called the improved three-fluid model, where the momentum relaxation time τ is assumed to depend on temperature in the superconducting and normal states, respectively, although τ has been assumed to be independent of temperature for the conventional three-fluid model. According to this model, the complex conductivity σ^^・ =σ_1-jσ_2 and the surface impedance Z_s=R_s+jX_s, where R_s is the surface resistance and X_s is the surface reactance, are expressed as a function of temperature. The temperature dependences of Z_s and σ^^・ for a YBCO bulk estimated using this model agree very well with ones measured by the dielectric-loaded cavity method in room to cryogenic temperature. In particular, a peak of σ_1 observed just below the critical temperature T_c in experiments, appeared in the calculated results based on this model. This phenomenon has been already known in the BCS theory. Thus, it is verified that this model is useful to explain the microwave characteristics of high-T_c superconductors in room to cryogenic temperature. On the other hand, the residual normal electron density n_<res>=4.254×10^<23> m^<-3> and the total electron density n_t=7.308×10^<24> m^<-3> are obtained by calculation. The ratio n_<res>n_t=0.058 can be used as figure of merit to evaluate material quality of high-T_c superconductors; thus it means that there is 5.8% nonpairing electron in this YBCO bulk.

収録刊行物

• IEICE Trans. Electron.

  IEICE Trans. Electron. 76 (8), 1275-1279, 1993

  一般社団法人電子情報通信学会

詳細情報

• CRID: 1573950402084043904
• NII論文ID: 110003220235
• NII書誌ID: AA10826283
• ISSN: 09168524
• 本文言語コード: en
• データソース種別:
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