Phason and amplitudon in the charge-density-wave phase of one-dimensional charge stripes in La2-xSrxCuO4

The present systematic Raman scattering experiments reveal the phason and amplitudon of the charge density wave (CDW) mode in the charge stripes of La2-xSrxCuO4. Only about 15% of the electronic density of states condenses into the CDW state. The symmetries of the CDW modes change by the rotation of the stripes at the insulator-metal transition. The energy of the phason is finite at 0.06 <= x <= 0.1 and zero at x=0.035 and 0.115 <= x <= 0.135, which suggests that the CDW is commensurate at 0.06 <= x <= 0.1 and incommensurate otherwise. The zero-energy phason seems to reduce T-c at x=1/8.