Gap mode, superconducting gap and phonon mode in V3Si and Nb3Sn

Abstract

In the high-T_c A15 compound V₃Si the authors found a Raman-active mode at a frequency of about 2 Delta . Peak frequency and intensity of this gap mode are strongly temperature-dependent. The temperature-dependence peak frequency compares well with the gap energy of the BCS theory. Thus one can investigate the superconducting gap with the help of Raman scattering. The intensity of the gap mode increases by about a factor of 20 if the temperature decreases from 14K to 5K. From the spectra of the gap mode and phonon mode in V₃Si and Nb₃Sn at various temperatures the authors draw the conclusion that the gap mode is coupled to the phonon mode.