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研究生: 林宗佑
Lin, Zong-You
論文名稱: 二維材料介面導致鐵薄膜磁耦合分離現象
Magnetic decoupling of ferromagnetic coverage across atomic step of MoS2 flakes on SiO2 surface
指導教授: 林文欽
Lin, Wen-Chin
學位類別: 碩士
Master
系所名稱: 物理學系
Department of Physics
論文出版年: 2018
畢業學年度: 106
語文別: 中文
論文頁數: 53
中文關鍵詞: 二硫化鉬磁性二維材料磁耦合分離
英文關鍵詞: MoS2, magnetism, two-dimensional material, magnetic decoupling
DOI URL: http://doi.org/10.6345/THE.NTNU.DP.007.2018.B04
論文種類: 學術論文
相關次數: 點閱:141下載:30
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  • 本實驗旨在於探討鐵磁薄膜沉積在單層二硫化鉬(MoS2)與二氧化矽基板(SiO2 /Si(100))兩種不同表面上產生的矯頑場(coercivity)差異,其鐵薄膜具有不連續的磁耦合分離性質,並分析推測此現象的可能來源。

    我們利用自製的化學氣相沉積系統(Chemical Vapor Deposition)合成大量二硫化鉬單層薄膜於二氧化矽基板,並以原子力顯微鏡(Atomic Force Microscope)、拉曼光譜儀(Raman spectrum)驗證其大多為單層的厚度結構。其後於超高真空環境(10-9 torr)蒸鍍鐵薄膜於其上,再以磁光科爾顯微鏡(magneto optical kerr mi-croscope)量測之。結果上,我們發現樣品表面的磁滯曲線(hysteresis loop)呈現非方正的鐵磁曲線,呼應我們對於鐵膜微觀表面上具有許多磁性粒子團的預測,且異質介面導致鐵薄膜在不同介面上有著相異的矯頑場,是為鐵薄膜磁耦合分離現象,此現象伴隨著鐵薄膜厚度提升而逐漸消失。

    In this study, we deposited Fe films on MoS2 flakes, and investigated the microscopic magnetic behavior on individual flake. The MoS2 flakes were fabricated on SiO2/Si(100) substrates using chemical vapor deposition. Fe coverage was deposited on the MoS2 flakes by e-beam evaporation with a thin Pd capping for the protection. Investigations by atomic force microscope and Raman spectroscopy confirmed that the MoS2 flakes were of the lateral size: 10-20 µm and mostly single layer thick. Af-ter depositing 3.6-7.0 nm Fe on MoS2/SiO2, clear hysteresis loops were observable with the in-plane magnetic field. From the investigation using a magneto-optical Kerr microscope, we measured the hysteresis curves of individual MoS2 flakes. Alt-hough the Fe coverage was much thicker than the MoS2 atomic step height (∼0.66 nm) and the direct connection and strong ferromagnetic coupling between Fe/MoS2 and Fe/SiO2 was expected, the magnetic decoupling between the magnetic domains of Fe/MoS2 and Fe/SiO2 was surprisingly observed. For 3.6 nm Fe/MoS2, the magnetic coercivity (Hc) was 28±5 Oe, while in contrast, the Hc of 3.6 nm Fe/SiO2 ranged 58±5 Oe. With a thicker Fe coverage, the Hc of interface converged and the magnetic de-coupling became vague to observe. The distinct interface magnetic anisotropy of Fe on different substrates could be responsible for the observed magnetic decoupling across the MoS2 atomic step between Fe/MoS2 and Fe/SiO2 domains. These observa-tions will be valuable in combining a magnetic coverage with a single layer MoS2 for the future spintronic applications.

    致謝 I 摘要 II Abstract III 目錄 IV 第一章 緒論 1 1-1 研究動機與計畫 1 第二章 材料概念與原理 2 2-1 二維材料 2 2-2 磁性材料 4 2-3 磁滯現象 6 2-4 磁光柯爾效應 8 第三章 實驗儀器與運作原理 11 3-1 磁光柯爾顯微鏡(Magneto Optical Kerr Microscope) 11 3-2 超高真空系統(Ultra-high vacuum system) 14 3-3 電子束蒸鍍系統(Electron beam evaporation) 18 3-4 化學氣相沉積系統(Chemical Vapor Deposition) 21 3-5 拉曼光譜儀系統(Raman spectrometer) 23 3-6 原子力顯微鏡(Atomic Force Microscope) 25 第四章 實驗製備與結果分析討論 29 4-1 MoS2 /SiO2樣品製備 29 4-2 MoS2 /SiO2拉曼光譜儀量測 33 4-3 MoS2 /SiO2原子力顯微鏡量測 35 4-4 Fe /MoS2 /SiO2樣品製備 36 4-5 Fe /MoS2 /SiO2樣品之磁性量測與分析 38 4-6 Co73Pd27(4 nm)/MoS2/SiO2樣品表面的沉積模式 43 4-7 結果與探討 48 第五章 總結 51 參考資料 52

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