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Phenomenological Description of Conduction Mechanism of HighT_{c} Superconductors by ThreeFluid Model
Yoshio KOBAYASHI Tadashi IMAI
Publication
IEICE TRANSACTIONS on Electronics
Vol.E74C
No.7
pp.19861992 Publication Date: 1991/07/25
Online ISSN: Print ISSN: 09168516 Type of Manuscript: Special Section PAPER (Special Issue on Low Temperature Electronics) Category: Keyword:
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Summary:
A new conduction mechanism of highT_{c} superconductors is proposed to interpret experimental results phenomenologically, which will be called a threefluid model, since nonpairing residual normal electron density n_{res} is added into the super electron density n_{s} and the normal electron density n_{n} for a wellknown twofluid model. According to this model, an admittance equivalent circuit of superconductor in unit cube is derived and n_{n}, n_{s}, the complex conductivity , the surface impedance Z_{s}, the skin depth δ, and the penetration depth λ are expressed as a function of temperature. Also such electron densities as n_{s}, n_{n}, and n_{res} are expressed as a function of Z_{s}. For Z_{s}, , δ, λ, n_{n}, and n_{s} of a YBCO plate, the values calculated by this model agree well in the range T0.9 T_{c} with the ones measured by the dielectric resonator method, where T_{c} is the critical temperature; thus the validity of this model is verified. Also the ratio n_{res}/n_{t}0.18 is determined by using n_{res}1.710^{24} m^{3} and n_{t}9.510^{24} m^{3} obtained from the measured Z_{s} values; thus it means that there is 18% nonpairing electron density in this YBCO plate. The ratio n_{res}/n_{t} can be used as figure of merit of highT_{c} superconductors.

