POLARON IMPRINTS IN THE INFRARED-SPECTRA OF ND2CUO4-Y

In addition to four E(u) phonons, Nd2CuO4-y single crystals show far-infrared reflectivity peaks which depend on temperature and y. They provide evidence for the insurgence of local modes induced by doping. The so called d- or J-band at approximately 1000 cm-1 can be partially resolved, and shown to be produced by combination bands of those local modes. These results provide direct evidence for polaron formation in this compound.