Chen Xiao-Jia, Struzhkin Viktor V, Wu Zhigang, Lin Hai-Qing, Hemley Russell J, Mao Ho-kwang
Geophysical Laboratory, Carnegie Institution of Washington, Washington, DC 20015, USA.
Proc Natl Acad Sci U S A. 2007 Mar 6;104(10):3732-5. doi: 10.1073/pnas.0611473104. Epub 2007 Feb 26.
High-temperature superconductivity in cuprates was discovered almost exactly 20 years ago, but a satisfactory theoretical explanation for this phenomenon is still lacking. The isotope effect has played an important role in establishing electron-phonon interaction as the dominant interaction in conventional superconductors. Here we present a unified picture of the oxygen isotope effect in cuprate superconductors based on a phonon-mediated d-wave pairing model within the Bardeen-Cooper-Schrieffer theory. We show that this model accounts for the magnitude of the isotope exponent as functions of the doping level as well as the variation between different cuprate superconductors. The isotope effect on the superconducting transition is also found to resemble the effect of pressure on the transition. These results indicate that the role of phonons should not be overlooked for explaining the superconductivity in cuprates.
铜酸盐中的高温超导现象几乎是在整整20年前被发现的，但对于这一现象仍缺乏令人满意的理论解释。同位素效应在确立电子 - 声子相互作用作为传统超导体中的主导相互作用方面发挥了重要作用。在此，我们基于巴丁 - 库珀 - 施里弗理论中的声子介导d波配对模型，给出了铜酸盐超导体中氧同位素效应的统一图景。我们表明，该模型解释了同位素指数随掺杂水平的变化以及不同铜酸盐超导体之间的差异。还发现同位素对超导转变的影响类似于压力对转变的影响。这些结果表明，在解释铜酸盐中的超导现象时，声子的作用不应被忽视。
