title: Hyper-Raman and Raman scattering from the polar modes of PbMg1/3Nb2/3O3.
abstract: Microhyper-Raman spectroscopy of PbMg(1/3)Nb(2/3)O(3) (PMN) single crystal is performed at room temperature. The use of an optical microscope working in backscattering geometry significantly reduces the LO signal, highlighting thereby the weak contributions underneath. We clearly identify the highest frequency transverse optic mode (TO3) in addition to the previously observed soft TO-doublet at low frequency and TO2 at intermediate frequency. TO3 exhibits strong inhomogeneous broadening but perfectly fulfils the hyper-Raman cubic selection rules. The analysis shows that hyper-Raman spectroscopy is sensitive to all the vibrations of the average cubic Pm3¯m symmetry group of PMN, the three polar F1u- and the silent F2u-symmetry modes. All these vibrations can be identified in the Raman spectra alongside other vibrational bands likely arising from symmetry breaking in polar nanoregions.
authors.affiliation: Laboratoire Charles Coulomb, UMR 5221, CNRS and Université Montpellier II, F-34095 Montpellier, France.
authors.forename: B
authors.initials: B
authors.lastname: Hehlen
authors.forename: A
authors.initials: A
authors.lastname: Amouri
authors.forename: A
authors.initials: A
authors.lastname: Al-Zein
authors.forename: H
authors.initials: H
authors.lastname: Khemakhem
mesh_terms: D007854:Lead / Q000737:chemistry*; D008274:Magnesium / Q000737:chemistry*; D009556:Niobium / Q000737:chemistry*; D010100:Oxygen / Q000737:chemistry*; D012542:Scattering, Radiation; D013055:Spectrophotometry, Infrared; D013059:Spectrum Analysis, Raman; D014732:Vibration
chemical_list: D009556:Niobium; D007854:Lead; D008274:Magnesium; D010100:Oxygen