摘要
We present an optical reflectance and Raman-scattering study of the (Formula presented) system as a function of temperature and doping (Formula presented) The metal-semiconductor transition in the (Formula presented) system is characterized by a change from a diffusive electronic Raman-scattering response in the high-temperature paramagnetic phase, to a flat continuum scattering response in the low-temperature ferromagnetic phase. We interpret this change in the scattering response as a crossover from a small-polaron-dominated regime at high temperatures to a large-polaron-dominated low-temperature regime. Interestingly, we observe evidence for the coexistence of large and small polarons in the low-temperature ferromagnetic phase. We contrast these results with those obtained for (Formula presented) which is a low-(Formula presented) magnetic semiconductor with similar properties to the manganites, but with a substantially reduced carrier density and polaron energy.
原文 | 英語 |
---|---|
頁(從 - 到) | 2795-2801 |
頁數 | 7 |
期刊 | Physical Review B - Condensed Matter and Materials Physics |
卷 | 58 |
發行號 | 5 |
DOIs | |
出版狀態 | 已發佈 - 1998 |
對外發佈 | 是 |
ASJC Scopus subject areas
- 電子、光磁材料
- 凝聚態物理學