Low frequency phonon model in YxPr1−xBa2Cu3O7 system

Abstract In order to explore how important the electron–phonon coupling is in high T c superconductors, we calculate the phonon frequencies at Gamma-point of the Y x Pr 1− x Ba 2 Cu 3 O 7 system by considering a special local structure in the Y x Pr 1− x Ba 2 Cu 3 O 7 , which is so called “fixed triangle”. It is found that a low frequency mode is possibly caused by the “fixed triangle” and roughly matches the experiment of Raman spectrum, which suggests that the coupling between electron and phonon is of importance in this system.