Unified picture of the oxygen isotope effect in cuprate superconductors.
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.
Chen
Xiao-Jia
XJ
Geophysical Laboratory, Carnegie Institution of Washington, Washington, DC 20015, USA. xjchen@ciw.edu
Struzhkin
Viktor V
VV
Wu
Zhigang
Z
Lin
Hai-Qing
HQ
Hemley
Russell J
RJ
Mao
Ho-kwang
HK