Symmetry of phonon, magnetic, and spin-phonon excitations in GdSr{sub 2}RuCu{sub 2}O{sub 8} single crystals
We present a polarized Raman scattering study of GdSr{sub 2}RuCu{sub 2}O{sub 8} single crystals. In this compound, the RuO{sub 6} octahedra are rotated around the c axis that in turn gives some Raman activity of the oxygen (O{sub Ru}) vibrations at 265 cm{sup -1} (A{sub 1g}), 411 cm{sup -1} (B{sub 2g}) and 607 cm{sup -1} (B{sub 1g}). These vibrations, as well as those of the apical oxygen of RuO{sub 6} at 654 cm{sup -1} (A{sub 1g}) and the Cu-plane oxygen at 318 cm{sup -1} (B{sub 2g}), clearly respond to the onset of magnetic ordering at T{sub m}{approx}140 K. In particular, the 265 cm{sup -1} mode hardens anomalously with decreasing temperature below T{sub m}. Notably, the corresponding phonon line is absent in the Raman spectra of GdSr{sub 2}NbCu{sub 2}O{sub 8} (Nb{sup 5+}:4d{sup 0}), a compound isomorphic to GdSr{sub 2}RuCu{sub 2}O{sub 8} (Ru{sup 5+}:4d{sup 3}). We argue that the eigenvector of the 265 cm{sup -1} phonon (rotational mode) facilitates efficient modulation of the Ru(t{sub 1g})-O{sub Ru}(p) bands. This modulation gives both Raman scattering strength to the 265 cm{sup -1} mode and strong spin-phonon coupling.
- Research Organization:
- Lawrence Berkeley National Laboratory
- Sponsoring Organization:
- (US)
- DOE Contract Number:
- AC03-76SF00098
- OSTI ID:
- 40277649
- Report Number(s):
- LBNL-49892; TRN: US0110184
- Journal Information:
- Physical Review B, Vol. 64, Issue 13; Other Information: DOI: 10.1103/PhysRevB.64.134304; Othernumber: PRBMDO000064000013134304000001; 047137PRB; PBD: 1 Oct 2001; ISSN 0163-1829
- Publisher:
- The American Physical Society
- Country of Publication:
- United States
- Language:
- English
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