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http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/97463完整後設資料紀錄
| DC 欄位 | 值 | 語言 |
|---|---|---|
| dc.contributor.advisor | 白奇峰 | zh_TW |
| dc.contributor.advisor | Chi-Feng Pai | en |
| dc.contributor.author | 黃書鋒 | zh_TW |
| dc.contributor.author | Shu-Feng Huang | en |
| dc.date.accessioned | 2025-06-18T16:15:27Z | - |
| dc.date.available | 2025-06-19 | - |
| dc.date.copyright | 2025-06-18 | - |
| dc.date.issued | 2025 | - |
| dc.date.submitted | 2025-06-09 | - |
| dc.identifier.citation | [1] Liu, Y.-T., et al., Determination of spin-orbit-torque efficiencies in heterostructures with in-plane magnetic anisotropy. Physical Review Applied, 2020. 13(4): p. 044032.
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| dc.identifier.uri | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/97463 | - |
| dc.description.abstract | 本研究探討在合成反鐵磁（Synthetic Antiferromagnet,SAF）結構中，鐵磁層厚度差（Δt）對自旋軌道轉矩（Spin-Orbit Torque, SOT）效率的影響。採用不同厚度組合的Pt-與W基底SAF系統，利用黃光微影、磁控濺鍍等製程製作出微米級霍爾元件，並透過各種電磁量測方法，包括各向異性磁阻（AMR）位移、單向自旋霍爾磁阻（USMR）、振動樣品磁強計（VSM）與縱向磁光克爾效應（L-MOKE）等，系統性分析了SOT效率與結構參數之關聯。研究結果指出，在對稱（Δt ≈ 0）的SAF結構中，可獲得最大之單位電流有效場（H_eff/I），顯著提升SOT效率，並且有效抑制淨磁化與偶極場。同時，W基SAF系統由於其較大的負自旋霍爾角，展現出更高的USMR與SOT效應。此外，與單層結構比較後，雖然SAF可提供熱穩定性與低功耗操作優勢，但在高電流下的USMR強度略低，顯示結構對稱性與厚度不均將影響自旋電流分佈與界面散射機制。本研究提供具體實驗證據，證明鐵磁層厚度設計在提升SOT-MRAM元件效能中的關鍵角色，並為次世代自旋電子記憶體之結構優化提供實用準則。此研究評估了場型自旋軌道轉矩（field-like spin-orbit torque, FL-SOT）之效率，以更深入解析其對轉矩機制的貢獻。透過 AMR Loop-shift所導出的單位電流有效場分析，可觀察 Pt-與 W-基 SAF 結構在鐵磁層厚度與結構不對稱變化下的 FL-SOT 效率趨勢。其中，對稱結構（Δt = 0）具備最佳 FL-SOT 效率，歸因於其具備平衡之自旋電流吸收能力。此結果凸顯出鐵磁層厚度設計能提升對場型轉矩效率之優化具關鍵意義，對於低功耗自旋電子元件的設計具有重要啟示。 | zh_TW |
| dc.description.abstract | This thesis investigates the impact of ferromagnetic (FM) layer thickness asymmetry (Δt) on spin-orbit torque (SOT) efficiency in synthetic antiferromagnet (SAF) structures. Pt-based and W-based SAF devices with varying FM thicknesses were fabricated using photolithography and magnetron sputtering. Multiple characterization techniques, including anisotropic magnetoresistance (AMR) loop-shift, unidirectional spin Hall magnetoresistance (USMR), vibrating sample magnetometry (VSM), and longitudinal magneto-optical Kerr effect (L-MOKE), were employed to evaluate the relationship between structural design and spin-torque efficiency. The results demonstrate that symmetric SAF configurations (Δt≈0) yield the highest effective field per current (H_eff/I), maximizing SOT efficiency while minimizing net magnetization and dipolar fields. W-based SAFs, with larger negative spin Hall angles, exhibit stronger USMR and SOT responses than their Pt-based counterparts. Compared to single-layer systems, SAF structures provide enhanced thermal stability and lower power operation; however, slightly reduced USMR magnitude at high current suggests that spin-current distribution and interface scattering are affected by layer symmetry and thickness mismatch.
Overall, this work provides experimental evidence of the critical role played by FM thickness engineering in optimizing SOT-driven switching performance and offers practical guidelines for future high-efficiency SOT-MRAM device design. The role of field-like spin-orbit torque (FL-SOT) efficiency provides further insight into spin-torque dynamics. By analyzing the current-induced effective field obtained from AMR loop shifts, both Pt-based and W-based SAF structures were found to exhibit distinct trends in FL-SOT efficiency as a function of ferromagnetic layer thickness and structural asymmetry. Notably, symmetric SAF configurations (Δt = 0) achieved the highest FL-SOT efficiency due to balanced spin-current absorption. This highlights the importance of optimizing FM thickness design not only for maximizing damping-like torque but also for enhancing FL-SOT performance in energy-efficient spintronic devices. | en |
| dc.description.provenance | Submitted by admin ntu (admin@lib.ntu.edu.tw) on 2025-06-18T16:15:27Z No. of bitstreams: 0 | en |
| dc.description.provenance | Made available in DSpace on 2025-06-18T16:15:27Z (GMT). No. of bitstreams: 0 | en |
| dc.description.tableofcontents | Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . i
摘要. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ii Abstract. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .iv Contents. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vi List of Figures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . x List of Equations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xv Chapter 1 Introduction and Theoretical Background 1 1.1 Spin Hall Effect 1 1.2 Spin-Orbit Torque Characterization 3 1.2.1 HM/FM Interface Mechanism 3 1.2.2 DC Current Switching by Spin-Orbit Torque 5 1.3 Introduction to Ruderman–Kittel–Kasuya–Yosida (RKKY) Interaction and Synthetic Antiferromagnets (SAF) 7 1.4 Motivation 11 Chapter 2 Experiments 13 2.1 Devices Fabrication Methods 13 2.1.1 Photolithography 13 2.1.2 Magnetron sputtering 14 2.2 Measurement Methods 16 2.2.1 Anisotropic Magnetoresistance loop-shift Measurement 16 2.2.2 Unidirectional Spin Hall Magnetoresistance (USMR) 20 2.2.3 Vibrating Sample Magnetometer (VSM) 23 2.2.4 Longitudinal-Magneto-Optical Kerr Effect (L-MOKE) Measurement 25 Chapter 3 Analysis of Single Ferromagnetic Layer 29 3.1 Field-Scan Unidirectional Magnetoresistance 29 3.1.1 Thickness-Dependent Unidirectional Spin Hall Magnetoresistance in Ferromagnetic Layer 29 3.1.2 Current-Dependent Unidirectional Spin Hall Magnetoresistance 31 3.1.3 Thickness-Dependent Effective Field per Current (∣H_eff/I∣) in Ferromagnetic Layer 33 3.1.4 Current-Dependent Effective Field per Current (∣H_eff/I∣) in Ferromagnetic Layer 36 3.2 Spin-Orbit-Torque Efficiencies 38 3.3 Comparison of Pt-based and W-based 40 Chapter 4 Analysis of Synthetic Antiferromagnets (SAF) 43 4.1 Field-Scan Unidirectional Magnetoresistance 43 4.1.1 Thickness-Dependent Unidirectional Spin Hall Magnetoresistance in Ferromagnetic Layer 43 4.1.2 Current-Dependent Unidirectional Spin Hall Magnetoresistance 48 4.1.3 Thickness-Dependent Effective Field per Current (∣H_eff/I∣) in Ferromagnetic Layer 50 4.1.4 Current-Dependent Effective Field per Current (∣H_eff/I∣) in Ferromagnetic Layer 52 4.1.5 Thickness Difference (Δt)-Dependent Effective Field per Current (∣H_eff/I∣) in Ferromagnetic Layer 55 4.2 Spin-Orbit-Torque Efficiencies 59 4.3 Comparison of Single Ferromagnetic Layer and Synthetic Antiferromagnets 64 4.4 Comparison of Pt-based and W-based 68 Chapter 5 Conclusion 73 Reference 75 | - |
| dc.language.iso | en | - |
| dc.subject | 自旋霍爾效應 | zh_TW |
| dc.subject | 自旋軌道轉矩 | zh_TW |
| dc.subject | 合成反鐵磁 | zh_TW |
| dc.subject | 鐵磁層厚度差 | zh_TW |
| dc.subject | 各向異性磁阻 | zh_TW |
| dc.subject | 單向自旋霍爾磁阻 | zh_TW |
| dc.subject | RKKY 交互作用 | zh_TW |
| dc.subject | 單位電流有效場 | zh_TW |
| dc.subject | Synthetic Antiferromagnet (SAF) | en |
| dc.subject | Ruderman–Kittel–Kasuya–Yosida (RKKY) Interaction | en |
| dc.subject | Effective Field per current (H_eff/I) | en |
| dc.subject | Ferromagnetic Layer Thickness Asymmetry | en |
| dc.subject | Anisotropy magnetoresistance (AMR) | en |
| dc.subject | Unidirectional Spin Hall Magnetoresistance (USMR) | en |
| dc.subject | Spin Hall Effect (SHE) | en |
| dc.subject | Spin-Orbit Torque (SOT) | en |
| dc.title | 合成反鐵磁中鐵磁層厚度不對稱調控之研究 | zh_TW |
| dc.title | Engineering Ferromagnetic Layer Thickness Asymmetry in Synthetic Antiferromagnets | en |
| dc.type | Thesis | - |
| dc.date.schoolyear | 113-2 | - |
| dc.description.degree | 碩士 | - |
| dc.contributor.oralexamcommittee | 魏拯華;楊朝堯 | zh_TW |
| dc.contributor.oralexamcommittee | Cheng-Hua Wei;Chao-Yao Yang | en |
| dc.subject.keyword | 合成反鐵磁,自旋軌道轉矩,自旋霍爾效應,單向自旋霍爾磁阻,各向異性磁阻,鐵磁層厚度差,單位電流有效場,RKKY 交互作用, | zh_TW |
| dc.subject.keyword | Synthetic Antiferromagnet (SAF),Spin-Orbit Torque (SOT),Spin Hall Effect (SHE),Unidirectional Spin Hall Magnetoresistance (USMR),Anisotropy magnetoresistance (AMR),Ferromagnetic Layer Thickness Asymmetry,Effective Field per current (H_eff/I),Ruderman–Kittel–Kasuya–Yosida (RKKY) Interaction, | en |
| dc.relation.page | 81 | - |
| dc.identifier.doi | 10.6342/NTU202501070 | - |
| dc.rights.note | 同意授權(限校園內公開) | - |
| dc.date.accepted | 2025-06-09 | - |
| dc.contributor.author-college | 工學院 | - |
| dc.contributor.author-dept | 材料科學與工程學系 | - |
| dc.date.embargo-lift | 2025-06-19 | - |
| 顯示於系所單位： | 材料科學與工程學系 | |
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