Raman scattering in the magnetically frustrated double perovskite Sr₂YRuO₆

Abstract

The spin correlations and excitations of the Sr2YRuO6 double perovskite are investigated by means of Raman scattering, complemented by synchrotron X‐ray diffraction measurements. Anomalous softening of a breathing mode of the oxygen octahedra is observed below ~200 K, much above the long‐range antiferromagnetic ordering temperature, TN1 = 32 K, due to a spin‐phonon coupling mechanism in the presence of magnetic correlations. A diffusive Raman signal is also observed, possibly associated with spin excitations within magnetically correlated regions. Our results point to a characteristic energy and temperature scale of ~25 meV/200 K below which unusual behavior associated with magnetic correlations is observed in this material. Copyright © 2013 John Wiley & Sons, Ltd.

Raman Spectroscopic Investigation and Electronic State Calculation for Ca2(Mn,Ti)O4 Black Pigments with High Near-Infrared (NIR) Reflectivity

“…The irreducible representations of the phonon modes at the Γ-point for the space group I 4 1 / acd (No. 142) are expressed as follows From the DFT phonon calculations, the pure Ca 2 MnO 4 lattice does not have Raman-active modes in the wavenumber region above 600 cm –1 but does have a silent A 2g mode at 739 cm –1 , similar to the A 1g (breathing) mode found in B -site-substituted single perovskite ( AB O 3 ) − and B -site ordered double perovskite structures ( A 2 B ′ B ″O 6 ). − A mechanical representation of the silent A 2g mode is illustrated in Figure . For example, a Raman peak at approximately 800 cm –1 corresponding to the breathing mode was previously observed for CaTiO 3 –NdAlO 3 solid solutions, except for the end members .…”

Evolution of the valence state of Ru metal ions in correlation with the structural and electronic properties of double perovskite ruthenates; A2SmRuO6 (where A = Ba & Sr)

“…In general, the Raman spectra of the BSRO and SSRO compounds are dominated by peaks observed at ∼355 cm −1 , 525 cm −1 & 760 cm −1 , the characteristic peaks for double perovskite materials. 31,32 The grouping of the normal modes at the Brillouin zone center for the double perovskite with cubic structure (space group: Fm 3̄ m ) of the BSRO compound are as follows:Γ cryst vib = Γ Ba + Γ Sm + Γ Ru + Γ O = A 1g (RA) + E g (RA) + F 1g (silent) + 2F 2g (RA) + 4F 1u (IR) + F 2u (silent)where, RA and IR represent Raman Active and Infrared Active, respectively. In BSRO compound F 1g and F 2u modes are both Raman & IR-inactive.…”

“…In general, the Raman spectra of the BSRO and SSRO compounds are dominated by peaks observed at B355 cm À1 , 525 cm À1 & 760 cm À1 , the characteristic peaks for double perovskite materials. 31,32 The grouping of the normal modes at the Brillouin zone center for the double perovskite with cubic structure (space group: Fm% 3m) of the BSRO compound are as follows:…”

Recent advances in linear and non‐linear Raman spectroscopy. Part IX

“…Garcia‐Flores and colleagues describe the results of Raman scattering in the magnetically frustrated double perovskite Sr 2 YRuO 6 . Their results point to a characteristic energy and temperature scale of ∼25 meV/200 K below which unusual behavior associated with magnetic correlations is observed in this material . Gasparov et al .…”