Study of Raman scattering in Ba-doped Bi-Sr-Cu-O single crystal

The phonon vibration characteristics of the Bi₂Sr_2-xBa_xCuO_y(x=0, 0.2, 0.4) single crystal samples was studied by using Raman scattering measurement. The results show that the typical phonon vibrational modes mainly appear in the frequency range of 196, 282-310, 460, 625 and 660 cm^-1, and the intensities of the 196, 282-310, 625 and 660 cm^-1 lines enhance with increasing Ba content x. The relationship between the incommensurate modulation structure and phonon vibration characteristics was analyzed, and it was found that the intensifying of the superstructure modulation (i.e. the decrease of modulation period) changes the symmetry of the unit cell seriously so that the phonon Raman activity of the unit cell varies significantly.