We present polarized Raman spectra from oriented single crystals of La2CuO4 and superconducting La1.85Sr0.15CuO4 that encompass the temperature range above and below the orthorhombic-to-tetragonal phase transition. This transition has a striking effect upon the Raman spectra. As approached from below (the orthorhombic phase), the ?zz spectrum from La2CuO4 shows a strong line at 104 cm-1 that broadens and softens and a weak line at 271 cm-1 that gradually disappears, both lines being unobservable in the tetragonal phase. The soft phonon is not seen in the orthorhombic phase of the Sr-doped sample, but the weak 271 cm-1 line is seen. The oxygen Eg mode of the tetragonal phase is observed to split into B2g and B3g components in the orthorhombic phase.
Raman investigation of the orthorhombic-tetragonal phase transition in La2-xSrxCuO4 superconductors
BE Watts
1988
Abstract
We present polarized Raman spectra from oriented single crystals of La2CuO4 and superconducting La1.85Sr0.15CuO4 that encompass the temperature range above and below the orthorhombic-to-tetragonal phase transition. This transition has a striking effect upon the Raman spectra. As approached from below (the orthorhombic phase), the ?zz spectrum from La2CuO4 shows a strong line at 104 cm-1 that broadens and softens and a weak line at 271 cm-1 that gradually disappears, both lines being unobservable in the tetragonal phase. The soft phonon is not seen in the orthorhombic phase of the Sr-doped sample, but the weak 271 cm-1 line is seen. The oxygen Eg mode of the tetragonal phase is observed to split into B2g and B3g components in the orthorhombic phase.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
