Direct Evidence of the Importance of Electron-Phonon Coupling in La2CuO4: Photoinduced IR Active Vibrational Modes

摘要

We present direct evidence of the importance of the electron phonon interaction in pure La2CuO4. A number of photoinduced IR active vibrational modes(IRAV)and associated bleaching of the La2CuO4 phonon modes are observed in the spectral range below 700/cm. The observation of photoinduced IRAV implies the existence of structural deformation around the photoexcited carriers, indicative of coupling of the photoexcitations to the lattice. We find, in addition, evidence of a broad photoinduced absorption at higher energies suggesting an electronic transition deep within the energy gap.