Carrier dynamics and infrared-active phonons in c-axis oriented RuSr2GdCU2O8 film

The conductivity spectra of c-axis oriented thin RuSr2GdCu2O8 film on SrTiO 3 substrate, prepared by pulsed-laser deposition, are obtained from the ana lysis of the reflectivity spectra over broad frequency range and temperatur es between 10 and 300 K. The free charge carriers are found to be strongly overdamped with their scattering rate (1.0 eV at room temperature) exceedin g the plasma frequency (0.55 eV). Four phonon lines are identified in the e xperimental spectra and assigned to the specific oxygen related in-plane po larized vibrations based on the comparison with the results of a lattice dy namics shell model calculations. (C) 2001 Elsevier Science B.V. All rights reserved.