BCS理论




BCS理论是解释常规超导体的超导电性的微观理论（所以也常意译为超导的微观理论）。该理论以其发明者约翰·巴丁、利昂·库珀和约翰·施里弗的名字首字母命名。




目录






  • 1 理論


  • 2 貢獻


  • 3 参见


  • 4 拓展阅读





理論


某些金属在极低的温度下，其电阻会完全消失，电流可以在其间无损耗的流动，这种现象称为超导。超导现象于1911年发现，但直到1957年，巴丁、库珀和施里弗提出BCS理论，其微观机理才得到一个令人满意的解释。BCS理论把超导现象看作一种宏观量子效应。它提出，金属中自旋和动量相反的电子可以配对形成所谓“库珀对”，库珀对在晶格当中可以无损耗的运动，形成超导电流。在BCS理论提出的同时，尼科莱·勃格留波夫（Nikolay Bogolyubov）也独立的提出了超导电性的量子力学解释，他使用的勃格留波夫变换（英语：Bogoliubov transformation）（Bogoliubov transformation）至今为人常用。


E=3.52kBTc1−(T/Tc){displaystyle E=3.52k_{B}T_{c}{sqrt {1-(T/T_{c})}}}E=3.52k_{B}T_{c}{sqrt {1-(T/T_{c})}}


电子间的直接相互作用是相互排斥的库伦力。如果仅仅存在库伦力直接作用的话，电子不能形成配对。但电子间还存在以晶格振动（声子）为媒介的间接相互作用：電聲子交互作用。电子间的这种相互作用在满足一定条件时，可以是相互吸引的，正是这种吸引作用导致了“库珀对”的产生。大致上，其机理如下：电子在晶格中移动时会吸引邻近格点上的正电荷，导致格点的局部畸变，形成一个局域的高正电荷区。这个局域的高正电荷区会吸引自旋相反的电子，和原来的电子以一定的结合能相结合配对。在很低的温度下，这个结合能可能高于晶格原子振动的能量，这样，电子对将不会和晶格发生能量交换，也就没有电阻，形成所谓“超导”。



貢獻


巴丁、库珀、施里弗因此获得1972年的诺贝尔物理学奖。不過BCS理論并無法成功的解釋所謂第二類超導，或高溫超導的現象。



参见


  • 超导


拓展阅读



  • 关于BCS理论的介绍，可以参见施里弗所著的面向研究生的优秀教材Theory of Superconductivity, ISBN 0-7382-0120-0.

  • ScienceDaily: Physicist Discovers Exotic Superconductivity（University of Arizona）August 17, 2006

  • Hyperphysics page on BCS

  • BCS History


  • Dance Analogy of BCS theory as explained by Bob Schrieffer (audio recording)




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