Magnetic field dependence on transition temperature Tc in cuprate superconductors

We investigate the magnetic field dependence on T_c in the high transition temperature superconductors. It is shown that phonon-enhanced spin fluctuations drive this superconductivity once more suggested by us [Phys. Rev. B 61 (2001) 4289]. We know magnetic field dependence on our transition temperature is in good correspondence with experimental data. It is elucidated that the external field is closely related to the local internal field in order to influence spin fluctuations.