Soft mode behavior and evidence for pressure-induced magnetostructural effects in Pr2 O3

The energetic proximity of crystal electric field (CEF) to phonon excitations in rare-earth materials can lead to strong electron-phonon coupling, exotic behavior, and technologically useful properties. We present a temperature-, pressure-, and magnetic field-dependent Raman scattering study of Pr2O3 that reveals soft phonon mode behavior and anomalies associated with CEF excitations, which are indicative of strong phonon-CEF coupling. We also show that both an applied magnetic field and pressure induce a similar splitting of the doubly degenerate Γ3 crystal-field level, providing evidence for pressure-induced magnetostructural effects in Pr2O3. These results demonstrate the importance of low-lying CEF excitations and strong CEF-phonon coupling in governing the phases and properties of rare-earth materials.