Pressure dependence of Tc and electron phonon interaction in MBa2Cu3O7 systems

Existing data for the pressure derivatives of critical temperatures Tc in the MBa2Cu3O7-y family are analyzed (M = Y, or rare earth). Using a two-dimensional BCS model, the electron-phonon coupling parameter is shown to be responsible for the increase of Tc, which varies with y in the same way as under an equivalent internal pressure. The anharmonic barium symmetrical stretching mode is compared with similar phonons in other 1-D or 2-D quasi-low-dimensional structures. A possible mechanism for large electron-phonon interaction and electron-electron pairing is proposed