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See detailSuppression of the cooperative Jahn-Teller distortion and its effect on the Raman octahedra-rotation modes of TbMn1-xFexO3
Vilarinho, R.; Passos, D. J.; Queiros, E. C. et al

in PHYSICAL REVIEW B (2018), 97(14),

This work reports the changes in structure and lattice dynamics induced by substituting the Jahn-Teller-active Mn3+ ion by the Jahn-Teller-inactive Fe3+ in TbMn1-xFexO3 over the full composition range ... [more ▼]

This work reports the changes in structure and lattice dynamics induced by substituting the Jahn-Teller-active Mn3+ ion by the Jahn-Teller-inactive Fe3+ in TbMn1-xFexO3 over the full composition range. The structural analysis reveals that the amplitude of the 0 (pure 0.5, where it is completely suppressed. We then correlate this evolution with the behavior of the Raman modes across the solid solution. In particular, we show that the Raman modes associated with the rotation of octahedra, whose wave number is commonly considered to scale linearly with the tilt angles in orthorhombic Pnma perovskites are also sensitive to the amplitude of the Jahn-Teller distortion. [less ▲]

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See detailMultiple strain-induced phase transitions in LaNiO3 thin films
Weber, M. C.; Guennou, Mael UL; Dix, N. et al

in PHYSICAL REVIEW B (2016), 94(1),

Strain effects on epitaxial thin films of LaNiO3 grown on different single crystalline substrates are studied by Raman scattering and first-principles simulation. New Raman modes, not present in bulk or ... [more ▼]

Strain effects on epitaxial thin films of LaNiO3 grown on different single crystalline substrates are studied by Raman scattering and first-principles simulation. New Raman modes, not present in bulk or fully relaxed films, appear under both compressive and tensile strains indicating symmetry reductions. Interestingly, the Raman spectra and the underlying crystal symmetry for tensile and compressively strained films are different. Extensive mapping of LaNiO3 phase stability is addressed by simulations, showing that a variety of crystalline phases are indeed stabilized under strain. The calculated Raman frequencies reproduce the principal features of the experimental spectra, supporting the validity of the multiple strain-driven structural transitions predicted by the simulations. [less ▲]

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See detailPhonon Raman scattering of RCrO3 perovskites (R = Y, La, Pr, Sm, Gd, Dy Ho, Yb, Lu)
Weber, M. C.; Kreisel, Jens UL; Thomas, P. A. et al

in PHYSICAL REVIEW B (2012), 85(5),

We report a systematic investigation of orthorhombic perovskite-type RCrO3 powder samples by Raman scattering for nine different rare earth Y, La, Pr, Sm, Gd, Dy, Ho, Yb, and Lu). The room-temperature ... [more ▼]

We report a systematic investigation of orthorhombic perovskite-type RCrO3 powder samples by Raman scattering for nine different rare earth Y, La, Pr, Sm, Gd, Dy, Ho, Yb, and Lu). The room-temperature Raman spectra and the associated phonon mode assignment provide reference data for structural investigation of the whole series of RCrO3 orthochromites and phonon ab-initio calculations. The assignment of the chromite spectra and comparison with Raman data on other orthorhombic perovskites allows correlating the phonon modes with the structural distortions in the RCrO3 series. In particular, two A(g) modes are identified as octahedra rotation soft modes, as their positions scale linearly with the octahedra tilt angle of the CrO6 octahedra. [less ▲]

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