Raman spectroscopy of RuSr2GdCu2O8 thin films

FAINSTEIN A, PANTOJA AE, TRODAHL HJ, MCCRONE JE, COOPER JR, GIBSON G, BARBER Z, TALLON JL

PHYSICAL REVIEW B - SOLID STATE

Año: 2001 vol. 63 p. 144505 - 144505

0556-2805

Polarization-resolved Raman data are reported for c-axis oriented thin films of RuSr2GdCu2O8 (Ru1212). The spectra show the same lines as were seen in polycrystalline ceramic material, although their relative intensities differ. A comparison of the film with polycrystalline spectra establishes that the strongest line at 650 cm(-1) shows a substantially reduced intensity in ab as compared to c-axis polarizations, which confirms the O(Sr) phonon assignment for the line. The line at 320 cm(-1), previously assigned as a B-1g-like O(Cu) mode, is seen particularly strongly in crossed polarizations, confirming its assignment as well, Finally, we observe spin-ordering-dependent features which are compared with similar phenomena reported earlier for the sintered material. As a function of decreasing temperature a line develops below the magnetic ordering temperature (T-M) and shifts up to similar to 130 cm(-1). An A(1g) symmetry phonon line observed at similar to 260 cm(-1), and which we assign to O(Ru) vibrations, hardens strongly below T-M. This latter peak, and the similar to 130 cm(-1) line, are substantially broader than in polycrystalline Ru1212. In addition, a diffusivelike laser tail characteristic of overdamped excitations (and which in retrospect is also weakly visible in polycrystalline Ru1212), is observed to disappear with decreasing temperature.