Abstract
Small polaron formation in transition metal oxides, like the prototypical material rutile TiO2, remains a puzzle and a challenge to simple theoretical treatment. In our combined experimental and theoretical study, we examine this problem using Raman spectroscopy of photoexcited samples and real-time time-dependent density functional theory (RT-TDDFT), which employs Ehrenfest dynamics to couple the electronic and ionic subsystems. We observe experimentally the unexpected stiffening of the A1g phonon mode under UV illumination and provide a theoretical explanation for this effect. Our analysis also reveals a possible reason for the observed anomalous temperature dependence of the Hall mobility. Small polaron formation in rutile TiO2 is a strongly nonadiabatic process and is adequately described by Ehrenfest dynamics at time scales of polaron formation.
Original language | English |
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Article number | 195165 |
Number of pages | 7 |
Journal | Physical Review B |
Volume | 96 |
Issue number | 19 |
DOIs | |
Publication status | Published - 29 Nov 2017 |
Keywords
- LATTICE-VIBRATIONS
- EXCESS ELECTRONS
- DYNAMICS
- DENSITY
- SPECTRA
- MOTION
- STATES
- DFT