Pyrochlore ``dynamic spin-ice'' Pr(2)Sn(2)O(7) and monoclinic Pr(2)Ti(2)O(7): A comparative temperature-dependent Raman study

Here we report a temperature-dependent Raman study of the pyrochlore ``dynamic spin-ice'' compound Pr(2)Sn(2)O(7) and compare the results with its non-pyrochlore (monoclinic) counterpart Pr(2)Ti(2)O(7). In addition to phonon modes, we observe two bands associated with electronic Raman scattering involving crystal field transitions in Pr(2)Sn(2)O(7) at similar to 135 and 460 cm(-1) which couple strongly to phonons. Anomalous temperature dependence of phonon frequencies that are observed in Pyrochlore Pr(2)Sn(2)O(7) are absent in monoclinic Pr(2)Ti(2)O(7). This, therefore, confirms that the strong phonon-phonon anharmonic interactions, responsible for the temperature-dependent anomalous behavior of phonons, arise due to the inherent vacant sites in the pyrochlore structure. (C) 2011 Elsevier Inc. All rights reserved.