異質結構鐵磁材料/高溫超導材料：La2/3Ca1/3MnO3/YBa2Cu3O7-x薄膜之不同接面研究

Ferromagnetism and superconductivity in La2/3Ca1/3MnO3 / YBa2Cu3O7-x heterostructure with different interfaces

呂宗諺(Cheng-Yan Lu)

指導教授 ： 林俊源

國立交通大學/理學院/物理研究所/碩士(2011年)

https://doi.org/10.6842/NCTU.2011.00764

摘要

本論文藉由脈衝雷射鍍膜(Pulse Laser Deposition，PLD)的技術探討 鐵磁材料與高溫超導材料(Ferromagnetic/Superconducting)的雙層薄膜(bilayers)在不同接面(La,Ca-O/Cu-O & Mn-O/Ba-O)產生的效應。我們選用的是龐磁阻材料La2/3Ca1/3MnO3與高溫超導材料YBa2Cu3O7-x 。利用同步輻射中心X光源進行X近緣吸收結構(XANES)實驗，探討Mn L-edge在不同接面上所發生的電子結構改變，以及LD(Linear Dichroism)效應。實驗發現不同接面的吸收光譜有明顯的能量偏移，原因是因為Mn和Cu在接面上週遭環境與單一塊材的不同，使得電子軌域重新排列，造成Mn 3d與O p軌域交互作用有所不同。而我們用LD(Linear Dichroism)驗證了Mn的3d軌域確實在不同接面的情況下軌域組成有所變化，使得LD(Linear Dichroism)效應顯著。

關鍵字

異質結構 ； 鐵磁材料 ； 高溫超導材料 ； 接面

並列摘要

In this study, epitaxial bilayers of ferromagnetic of La2/3Ca1/3MnO3 (LCMO) and superconducting YBa2Cu3O7-x (YBCO) were grown on SrTiO3 (001) substrates by pulsed laser deposition assisted with high pressure reflection high energy electron diffraction. Two different interfaces (La,Ca-O/Cu-O & Mn-O/Ba-O) have been designed and created to be a model template to understand the coupling behaviors at the interfaces. X-ray absorption near edge spectroscopy (XANES) have been applied to study the electronic structures of LCMO/YBCO with different interfaces. We demonstrate that extensive charge transfer occurs between LCMO and YBCO. In addition, our experiments show there is obvious energy shift in the absorption spectrum Mn L edge of different interfaces. Different interfaces lead to the difference of orbital reconstructions, which confirmed by linear dichroism (LD) effect. This study opens new venue to design the functional interfaces.

並列關鍵字

Ferromagnetism ； superconductivity ； heterostructure ； interfaces

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