Raman spectroscopy of ordered double perovskiteLa2CoMnO6thin films

Abstract

The Raman spectra of epitaxial thin films of La 2 CoMnO 6 on ͑001͒-oriented SrTiO 3 substrates have been measured in several exact scattering configuration between 12 and 890 K. The polarization dependence of the spectra provide clear evidence for ordered P12 1 / n1 structure, differing from its parent Fm3m structure by the presence of rotational distortions. The correlation between the phonon modes in Fm3m, R3, and P12 1 / n1 phases is analyzed and the corresponding types of atomic motions as well as their expected frequency range are determined by comparison to the predictions of lattice dynamical calculations. The ferromagnetic ordering and spin-phonon coupling below T C result in softening of some of the phonon modes. The evolution of the Raman spectra at high temperatures shows no indication for P12 1 / n1-R3 transition up to 800 K.

Electronic and magnetic properties of La2NiMnO6 and La2CoMnO6 with cationic ordering

“…[14][15][16][17][18] Meanwhile, LCMO thin films can be grown on cubic (001) SrTiO 3 substrates by pulsed laser deposition. 19 Either in the form of bulk or films, local Co/Mn or Ni/Mn disorder has been observed which results in the coexistence of multi phases with various behaviors. [3][4][5][6][7][8][9][10] The distinct disorder effects in LNMO and LCMO thus call for the first-principle investigation for effect of cation ordering, but such kind of calculation does not exist.…”

Raman-scattering study ofKxSr1−xFe2As2Litvinchuk1, Hadjiev2, Iliev3 et al. 2008Phys. Rev. BSelf Cite10081151View full textAdd to dashboardCite

“…We also performed shell-model calculations of the lattice dynamics using the general utility lattice program ͑GULP͒, 16 which is known to reasonably describe a wide class of ionic materials ͑oxides in particular͒. 17,18 In the shell model each ion is considered as a point core with charge Y surrounded by a massless shell with charge Q. The free-ion polarizability is accounted for by the force constant k. The short-range potentials V͑r͒ are chosen in the Born-Mayer-Buckingham form V͑r͒ = a exp͑− r/r 0 ͒ − cr −6 .…”

Spin-Electron-Phonon Excitation in Re-based Half-Metallic Double Perovskites

“…This structure allows for four Raman-active vibration modes (A 1g + E g + 2F 2g ), three of them (A 1g + E g + F 2g ) involving mostly displacements of the oxygen ions that compose the octahedral environment of the transition-metal ions (see Fig. 1(a)) [13], while the remaining lower-frequency F 2g mode involves mostly displacements of the A ions. The A 1g symmetric stretching mode is of particular interest since it modulates the volume of the MO 6 and ReO 6 octahedra and therefore the chemical pressure of the oxy-gen cages onto the transition-metal ions.…”