Pyrochlore “dynamic spin-ice” Pr2Sn2O7 and monoclinic Pr2Ti2O7: A comparative temperature-dependent Raman study

Here we report a temperature-dependent Raman study of the pyrochlore “dynamic spin-ice” compound Pr2Sn2O7 and compare the results with its non-pyrochlore (monoclinic) counterpart Pr2Ti2O7. In addition to phonon modes, we observe two bands associated with electronic Raman scattering involving crystal field transitions in Pr2Sn2O7 at ∼135∼135 and 460 cm−1 which couple strongly to phonons. Anomalous temperature dependence of phonon frequencies that are observed in pyrochlore Pr2Sn2O7 are absent in monoclinic Pr2Ti2O7. 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.

The phonon–phonon anharmonic interaction which is responsible for the temperature-dependent anomalous behavior of phonons, arise due to the inherent vacant sites in the pyrochlore structure.Figure optionsDownload as PowerPoint slideHighlights
► Pyrochlore Pr2Sn2O7 and its monoclinic counterpart Pr2Ti2O7 are compared.
► Raman spectroscopic data reveal temperature-dependent phonon anomalies.
► Crystal field transitions in Pr2Sn2O7 couple with phonons.
► Phonon anomalies are attributed to phonon–phonon anharmonic interactions.
► Phonon anharmonicity in pyrochlores arise due to their inherent vacancies.