Raman spectroscopy of RuSr2GdCu2O8 thin films
Abstract
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 B1g-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 (TM) and shifts up to ~130 cm-1. An A1g symmetry phonon line observed at ~260 cm-1, and which we assign to O(Ru) vibrations, hardens strongly below TM. This latter peak, and the ~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.
- Publication:
-
Physical Review B
- Pub Date:
- April 2001
- DOI:
- 10.1103/PhysRevB.63.144505
- Bibcode:
- 2001PhRvB..63n4505F
- Keywords:
-
- 74.72.Jt;
- 74.76.Db;
- 74.25.Ha;
- 78.30.-j;
- Other cuprates including Tl and Hg-based cuprates;
- Magnetic properties;
- Infrared and Raman spectra