Importance of structural instability to high-temperature superconductivity.
Published Web Locationhttps://doi.org/10.1103/physrevlett.67.512
The orthorhombic-tetragonal structural phase transition of La2-xSrxCuO4 is quantitatively analyzed as a function of composition x within an anharmonic electron-phonon interaction model. The correct temperature dependence of the soft mode and the elastic constant c66 is obtained. The double-well potential in the electron-phonon interaction is derived self-consistently and found to vary strongly with x. In the vicinity of the superconducting transition temperature Tc electrontwo-phonon interactions dominate the harmonic ones which may explain the high Tcs observed. © 1991 The American Physical Society.