Symmetry of phonon, magnetic, and spin-phonon excitations in GdSr{sub 2}RuCu{sub 2}O{sub 8} single crystals

Journal Article · Mon Oct 01 04:00:00 EDT 2001 · Physical Review B

DOI:https://doi.org/10.1103/PhysRevB.64.134304· OSTI ID:40277649

Hadjiev, V G; Baeckstroem, J; Popov, V N; Iliev, M N; Meng, R L; Xue, Y Y; Chu, C W

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
• Journal Information: Physical Review B, Journal Name: Physical Review B Journal Issue: 13 Vol. 64; ISSN 0163-1829
• Publisher: The American Physical Society
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
EIGENVECTORS
MODULATION
MONOCRYSTALS
OXYGEN
PHONONS
RAMAN SPECTRA
SCATTERING
SYMMETRY