Temperature-dependent Raman Scattering Studies of the Geometrically Frustrated Pyrochlores Dy2Ti2O7, Gd2Ti2O7 and Er2Ti2O7
M. Maczka; J. Hanuza; K. Hermanowicz; A.F. Fuentes; K. Matsuhira; Z. Temperature-dependent Raman Scattering Studies of the Geometrically Frustrated Pyrochlores Dy2Ti2O7, Gd2Ti2O7 and Er2Ti2O7 . Journal of Raman Spectroscopy (ISSN: 0377-0486). 2008, Vol. 39 [4] , p. 537-2008.
The temperature-dependent Raman studies of A2Ti2O7 (A = Dy, Er, Gd) were performed in single crystals and polycrystalline samples in the 4.2-295 K temperature range. The Raman spectra showed softening upon cooling of the majority of phonon modes in the whole temperature range studied and large decrease of linewidths. These changes have been analyzed in terms of strong third-order phonon-phonon anharmonic interactions. Moreover, the 312 and 330 cm-1 modes of Er2Ti2O7 (Gd2Ti2O7) showed hardening upon cooling down to about 130 K (100 K) and then anomalous softening below this temperature. The observed anomalous behavior of Raman modes indicates that some important changes occur in these materials at low temperatures. However, the origin of this behaviour is still not clear.
The temperature-dependent Raman studies of A2Ti2O7 (A = Dy, Er, Gd) were performed in single crystals and polycrystalline samples in the 4.2-295 K temperature range. The Raman spectra showed softening upon cooling of the majority of phonon modes in the whole temperature range studied and large decrease of linewidths. These changes have been analyzed in terms of strong third-order phonon-phonon anharmonic interactions. Moreover, the 312 and 330 cm-1 modes of Er2Ti2O7 (Gd2Ti2O7) showed hardening upon cooling down to about 130 K (100 K) and then anomalous softening below this temperature. The observed anomalous behavior of Raman modes indicates that some important changes occur in these materials at low temperatures. However, the origin of this behaviour is still not clear.