Structural properties of multiferroic CuFeO2 thin films prepared by RF sputtering

CuFeO2 thin films were grown on single crystalline sapphire substrates with c-axis orientation by rf sputtering method. The reitveld refinement analysis of X - ray diffraction data indicates the formation of delafossite structure and tended to be oriented along (001). Raman-scattering study of these thin films reveals that the films were oriented along (001) with rhombohedral R3??m symmetry. Temperature dependent Raman spectra of CuFeO2 thin films were measured from 80K to1273K and we observed two optical modes at Eg (296cm??1) and Ag (638cm??1) showing anomalous frequency shifts with temperature, which were interpreted as an experimental evidence of combined effect of lattice expansion and anharmonic phonon - phonon interaction in CuFeO2.