STRONG-COUPLING SUPERCONDUCTIVITY. I
STRONG-COUPLING SUPERCONDUCTIVITY. I
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DOI：
10.1103/physrev.148.263
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发表时间：
1966-08
期刊：
影响因子：
--
通讯作者：
D. Scalapino;J. Schrieffer;J. Wilkins
中科院分区：
文献类型：
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作者：
D. Scalapino;J. Schrieffer;J. Wilkins
将超导的配对理论推广到处理具有强电子-声子耦合的系统。在这种情况下，朗道准粒子近似是无效的。在理论中，我们把声子和库仑相互作用放在同一个基础上，并使用Nambu形式的非零温度绿色函数进行分析。在T= 0 K时，对近似代表铅的模型求解了由此得到的广义能隙方程，并绘制了复能隙参数Δ（ω）作为声子和库仑相互作用强度的几种选择的能量函数。导出了单粒子隧穿态密度的表达式，如果选择声子相互作用强度来给出零温下观察到的能隙Δ 0，则该表达式与Δ（ω）结合起来，与实验结果非常吻合.因此，隧穿实验为超导的声子机制和强耦合理论的有效性提供了详细的证明。另外，通过理论和隧穿实验的结合，我们可以对电子-声子相互作用和声子态密度有更多的了解。该理论的精确度为电子-离子质量比的平方根10 - 2-10 - 3。
The pairing theory of superconductivity is extended to treat systems having strong electron-phonon coupling. In this regime the Landau quasiparticle approximation is invalid. In the theory we treat phonon and Coulomb interactions on the same basis and carry out the analysis using the nonzero-temperature Green's functions of the Nambu formalism. The generalized energy-gap equation thus obtained is solved (at T= 0 K) for a model which closely represents lead and the complex energy-gap parameter Δ (ω)) is plotted as a function of energy for several choices of phonon and Coulomb interaction strengths. An expression for the single-particle tunneling density of states is derived, which, when combined with Δ (ω), gives excellent agreement with experiment, if the phonon interaction strength is chosen to give the observed energy gap Δ 0 at zero temperature. The tunneling experiments therefore give a detailed justification of the phonon mechanism of superconductivity and of the validity of the strong-coupling theory. In addition, by combining theory and the tunneling experiments, much can be learned about the electron-phon interaction and the phonon density of states. The theory is accurate to terms of order the square root of the electron-ion mass ratio,∼ 10− 2-10− 3.