三羥甲基胺基甲烷(8羥基喹啉)鐵(III)蒸鍍於鎳薄膜在銅(100)之介面電子結構與磁交互作用

Interfacial Electronic Structure and Magnetic Coupling of Tri(8-hydroxuquinoline)iron(III) on Ni/Cu(100)

謝宥詳(Yu-Hsiang Hsieh)

指導教授 ： 許瑤真 ； 李志浩

國立清華大學/原子科學院/先進光源科技學位學程/碩士(2021年)

摘要

本論文主要探討有機半導體分子(tris-(8-hydroxyquinoline) iron(III)，三羥甲基胺基甲烷(8羥基喹啉)鐵(III)，簡稱Feq3)蒸鍍於Ni/Cu(100)基板上的異質介面之電子結構、磁性性質、與自旋耦合等介面特性。實驗利用同步輻射能譜與顯微術測量在近自旋轉向厚度的金屬鎳薄膜與有機半導體分子Feq3之異質介面的交互作用行為，實驗結果顯示介面的Feq3分子在C、N、O 1s的光電子能譜訊號中有混合態(hybrid state)的形成，說明在介面上有很明顯的電荷轉移。另外，從近緣吸收結構光譜實驗中，可以發現Feq3與Ni基板接觸時，Feq3分子的中心鐵原子會從原本的Fe(III)還原成Fe (II)。最後從磁圓偏振二向性(XMCD)的實驗結果中，觀測到微弱的Fe L-edges XMCD訊號但無磁滯迴路的顯現。而在Ni L-edges 則仍保有XMCD的訊號以及磁滯迴路，其磁滯迴路明確顯示Feq3-Ni介面存在交換偏置場(exchange bias)的交互作用，代表在與Ni的介面上Feq3是一個反鐵磁性的材料。

關鍵字

電子結構 ； 磁性交互作用 ； 交換偏置場 ； 電荷轉移

並列摘要

This thesis mainly discusses the electronic structure, magnetic properties, and spin coupling of the heterogeneous interface of organic semiconductor molecules(tris-(8-hydroxyquinoline) iron(III)) deposited on Ni/Cu(100) substrate. The experiment uses synchrotron spectroscopy and microscopy to explore the interplay at the heterogeneous interface between the metallic nickel near the critical thickness of spin reoeientation transition(SRT) and the organic semiconductor molecule Feq3. We deposited Feq3 on nickle by thermal evaporation, and then utilized synchrotron x-ray photoelectron spectroscopy (XPS) and Near-Edge X-ray Absorption Fine Structure (NEXAFS) to probe the interfacial electronic properties of Feq3 on Ni, the XPS N 1s, C 1s, and O 1s signal exhibited two peaks corresponding to molecular state and hybridized states when a sub- to monolayer of Feq3 absorbed on Ni. NEXAFS spectra implied the central iron and Ni layer have charge transfer via strong interaction, that causes the central iron(III) reduces to iron(II). Finally, from the results of magnetic circular polarization dichroism (XMCD), a slight XMCD singal at Fe L-edges of Feq3 is observed, while Ni L-edges still displays siginicant XMCD signal but gradually reduced coercivity in hysteresis loop as a function of Feq3 thickness. The results suggest an antiferromagnetic coupling appear at Feq3-Ni heterojunction interface according to the exchange bias observed in the hysteresis loop. It means that Feq3 is an antiferromagnetic material at the interface contacting with Ni.

並列關鍵字

Electronic Structure ； Magnetic Coupling ； Exchange bias ； charge transfer

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