利用X光吸收光譜研究La0.85Zr0.15MnO3電子結構

The electronic structure of La0.85Zr0.15MnO3 studied by x-ray absorption spectroscopy

李鴻民(Hang-Ming Lee)

指導教授 ： 彭維鋒

淡江大學/理學院/物理學系碩士班/碩士(2009年)

https://doi.org/10.6846/TKU.2009.00412

摘要

本論文主要以X光吸收光譜實驗研究鑭鋯錳氧的電子與原子結構。實驗包含室溫下Mn K- 和O K- 與Mn L3,2-edge X光吸收近邊緣結構(X-ray absorption near edge structure，XANES)，以及分別在不同溫度和條件下量測O K-與Mn L3,2-edge XANES和Mn K-edge延伸X光吸收精細結構(Extended x-ray absorption fine structure，EXAFS)。由常溫下Mn K-edge和O K-與Mn L3,2-edge XANES得知樣品中錳的價數應為三價與四價間，所以樣品導電傳輸介子應為電洞(hole doped)。在變溫下Mn L3,2-edge與O K-edge XANES光譜圖中發現，在鐵磁金屬與反鐵磁絕緣區，O 2p和Mn
3d混合未佔據態強度因電荷轉移效應，呈相反趨勢。從變溫下Mn K-edge EXAFS 傅利葉轉換得知，因結構上的扭曲在電性與磁性相變點TMI (絕緣體轉金屬之溫度)、TC (反鐵磁轉鐵磁之溫度)前後有著急劇的改變，影響電性與磁性在相變點前後上的變化。

關鍵字

XANES ； EXAFS ； 錳

並列摘要

The electronic and atomic structures of the La0.85Zr0.15MnO3 were investigated by measuring the Mn K-, O K-, and Mn L3-edge x-ray absorption near-edge structure (XANES) and Mn K-edge extended x-ray absorption fine structure (EXAFS) at various temperatures. The Mn K- edge, O K-and Mn L3,2-edge XANES at room temperature indicated that Mn ions in the sample is between 3+ and 4+, thus the behavior of the sample is expected to be hole doped . The temperature-dependent O K-, and Mn L3,2-edge XANES spectra indicated that hybrization of the O 2p-Mn 3d unoccupied state has opposite tendency at the ferromagnetic metal and anti-ferromagnetic insulator region caused by charge transfer effect. EXAFS revealed both receptivity and magnetic susceptibility around the TMI (the transition temperature of metal to insulator) and TC (the transition temperature of anti-ferromagnet to ferromagnet) change significantly due to structural distortion.

並列關鍵字

XANES ； EXAFS ； Manganese

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