Resonant Raman signatures of exciton polarons in a transition metal oxide: BiVO_4
arxiv(2024)
摘要
In this work we investigate the delocalized excitons and excitons trapped by
a polaron formation in by means of resonant Raman spectroscopy. We
record Raman spectra with 16 laser lines between 1.9 and 2.6 and
analyze intensity variations of the Raman peaks for different vibrational
modes. The resonant Raman cross sections of the modes contain two types
of resonances. The first high-energy resonance near 2.45 belongs to a
transition between delocalized states; it is close to absorption edge measured
at 2.3 and exhibits a characteristic 50 anisotropy between
polarization parallel and perpendicular to the c axis. The high energy Raman
resonance occurs inside the gap at 1.94 for all crystallographic
directions.
The in-gap resonance can involve a localized transition. We attribute it to
an exciton-polaron, formed by a small localized electron polaron of Holstein
type and delocalized holes. It manifests in the vibrations of vanadium and
oxygen atoms where polaron localization occurs and the resonance energy matches
theoretical predictions. The vibrational modes couple to the polaron with
different efficiency determined from resonant Raman profiles.
更多查看译文
AI 理解论文
溯源树
样例
生成溯源树,研究论文发展脉络
Chat Paper
正在生成论文摘要