伴隨著人工智慧、大數據的蓬勃發展，近年來對於資料儲存的需求日漸增加。在現存主流的記憶體中如DRAM，SRAM皆為揮發類性記憶體。這類記憶體如須保持資料儲存則須不間斷的供應電流，因此在能量損耗上相當可觀。而現存的非揮發性記憶體如Flash則有著讀寫速度上的劣勢。
磁性記憶體MRAM由於其非揮發的性質以及優異的讀寫速度，因此普遍被視為下個世代的記憶體。本篇論文主要在建立於第三世代的自旋軌道力矩磁性記憶體的基礎上，引入反鐵磁材料作為輔助用以達成零場翻轉。然而由於使用的反鐵磁材料有著特殊的結構，我們發現了其有著與玻璃相似的性質並可以透過自旋軌道力矩進行塑型，而用以固定零場翻轉的極性。
我們也在現有的反鐵磁理論上加入了嶄新的架構用以描述反鐵磁結構的性質，這篇論文不僅僅達成了第三世代磁性記憶體中的零場翻轉，更是給予了未來的反鐵磁相關研究點了一盞明燈。

Antiferromagnetic material (AFM) attracted fervent attention due to its multifunctional characteristic, making it become the most promising next generation memory devices. Although AFM is integrated into several application in contemporary memory devices, the realistic understanding of AFM is far below typically used Ferromagnetic material (FM) however. This thesis proposed an innovate idea to describe AFM and reveals the hidden properties beneath existing Néel order theory and we can further modify the spin configuration in AFM through spin orbit torque (SOT). Owing to the peculiar 3Q spin texture in polycrystalline IrMn, the shaped IrMn can assisted field free switching without apparent symmetry breaking term. Additionally, the field free switching polarity is fixed after training and cannot be rewrite afterwards. All the properties of AFM are carefully characterized by advance optical and electrical methods. This work proposed a new theory of AFM material, and the memorable characteristic of AFM definitely turns over a new leaf into AFM based spintronics device.

Abstract I
摘要 II
Table of Contents III
List of Figures IV
List of abbreviations and notations VII
1 Introduction 1
2 Theory 3
2.1 Spin orbit torque 3
2.1.1 Charge and spin 3
2.1.2 Past, present and future of MRAM 3
2.1.3 Spin Hall effect 6
2.1.4 Rashba effect 7
2.1.5 Spin-orbit torque switching magnetic moment 8
2.2 Antiferromagnetism 12
2.2.1 Categories of antiferromagnet 12
2.2.2 Exchange bias 15
2.2.3 Field free switching in AFM SOT-MRAM 16
2.2.4 AFM spintronics 18
2.3 Magnetic Domain 22
2.3.1 Magnetic domain and domain wall 22
2.3.2 Domain wall dynamics 23
3 Experiment apparatuses 26
3.1 Thin film deposition 26
3.1.1 Ultra-high Vacuum Magnetron Sputtering System 26
3.2 Characterization 27
3.2.1 Atomic Force Microscopy 27
3.2.2 Vibration Sample Magnetometer 28
3.3 Micro-Device fabrication 29
3.3.1 Photolithography 29
3.3.2 Ion-Beam Etcher 30
3.4 Electrical properties measurement 31
3.4.1 Four-Point Probe Station 31
3.5 Spectroscopy 32
3.5.1 TPS-45A Submicron Soft X-ray Spectroscopy 32
4 Result and discussion 33
4.1 Experimental design 33
4.2 Magnetic properties in PMA HM/FM/AFM tri-layer 35
4.3 AHE and SOT switching 39
4.4 Glassy state property in polycrystalline IrMn 44
5 Conclusions and future prospects 54
6 References 55

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