Abstract
The electrodynamics near the metal-to-insulator transitions induced, in single crystals, by both temperature and pressure has been studied by infrared spectroscopy. The and dependence of the optical conductivity may be explained within a polaronic scenario. The insulating phase at ambient and corresponds to strongly localized small polarons. Meanwhile the -induced metallic phase at ambient pressure is related to a liquid of polarons showing incoherent dc transport, in the -induced metallic phase at room strongly localized polarons coexist with partially delocalized ones. The electronic spectral weight is almost recovered, in both the - and -induced metallization processes, on an energy scale of , thus supporting the key role of electron-lattice interaction in the metal-to-insulator transitions.
- Received 30 January 2007
DOI:https://doi.org/10.1103/PhysRevB.75.245108
©2007 American Physical Society