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研究生:高詩哲
研究生(外文):Shih-Che Kao
論文名稱:鈷鐵硼/鎢/鈷鐵硼系統之零外加場自旋軌道矩翻轉機制與表現
論文名稱(外文):Field-free spin-orbit torque switching in CoFeB/W/CoFeB system: mechanism and performance
指導教授:白奇峰
指導教授(外文):Chi-Feng Pai
口試委員:黃斯衍曲丹茹
口試委員(外文):Ssu-Yen HuangDan-Ru Qu
口試日期:2023-06-19
學位類別:碩士
校院名稱:國立臺灣大學
系所名稱:材料科學與工程學系
學門:工程學門
學類:材料工程學類
論文種類:學術論文
論文出版年:2023
畢業學年度:111
論文頁數:79
中文關鍵詞:自旋電子學自旋霍爾效應自旋軌道矩零外加場磁矩翻轉尼爾橙皮效應
外文關鍵詞:SpintronicsSpin Hall effectSpin-orbit torqueField-free SOT switchingNeel orange-peel effect
DOI:10.6342/NTU202301461
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隨著自旋霍爾效應和拉什巴效應的發現與應用,自旋軌道矩磁性隨機存取記憶體實現非揮發性存取技術、高資料密度及耐用性,在自旋軌道矩磁性隨機存取記憶體中,採用垂直異相性的系統提供了更快的讀寫速度以及更高儲存密度。然而,需要外加水平磁場克服對稱性進而翻轉磁矩一直以來都是個關鍵的挑戰,目前已有很多機制在不施加外加場的情況下實現磁矩翻轉,但考量到製程兼容性與整合可行性,只有其中的一部分機制已被驗證可應用在自旋軌道矩磁性隨機存取記憶體中,有鑑於具備高穿隧磁阻比的鈷鐵硼/氧化鎂結構已被應用在當今系統,一個建立在此結構的解決方案是值得探討的。
在本篇論文中,對同時具備平面異相性及垂直異相性的鈷鐵硼/鎢/鈷鐵硼結構進行了零外加場自旋軌道矩翻轉機制及尺寸微縮的深入探討。首先對材料架構進行解釋並量測系統的平面異相性,接著,分別進行了磁滯曲線平移和電流致磁矩翻轉量測,測定了自旋軌道矩功效及零外加場磁矩翻轉表現,透過在自旋軌道矩功效隨平面磁場的作圖中發現非典型的似磁滯曲線,證實了內置偏置磁場的存在,在角度相關的量測中,餘弦行為驗證平面磁矩與內置偏置磁場之間的平行關係。在排除該結構中其他可能造成零外加場磁矩翻轉的潛在機制後,我們將重點移到尼爾橙皮效應上,透過原子力顯微鏡從表面形貌得到的數據推算粗糙引起的尼爾場大小,與磁滯曲線平移實驗得到的測量值比較,提供了一個實驗與理論預測的橋樑。隨後,試片被製備成柱狀,即便尺寸微縮,零外加場磁矩翻轉的表現依舊維持。此外,我們也展示了其他結構工程像是楔形結構與加場沉積的數據結果。總體來說,本篇論文在粗糙引起零外加場磁矩翻轉的機制與初步尺寸微縮進行了詳細的探討。
With the discovery of spin-orbit torque (SOT), resulting from spin Hall effect (SHE) and/or Rashba effect, SOT-magnetic random access memory (SOT-MRAM) has revolutionized non-volatile memory technology by enabling high data storage density and great endurance. Among SOT-MRAMs, type-z geometry with perpendicular magnetic anisotropy (PMA) especially provides faster read/write switching speeds as well as higher storage density. However, the requirement of an external magnetic field to break the symmetry and facilitate magnetization switching has been a critical challenge. Several mechanisms have been proposed to achieve field-free magnetization switching without the aid of an external magnetic field. In consideration of compatibility with back end of line (BEOL) and its feasibility of integration, only a subset of them have been verified workable in SOT-MRAM system. Given that CoFeB/MgO structures with high tunneling magnetoresistance (TMR) ratio have been employed in existing systems, a field-free solution leveraging it is worth exploring.
In this thesis, a comprehensive investigation into field-free SOT switching mechanism and feasibility of scaling down are conducted on CoFeB/W/CoFeB T-type structures with both in-plane and out-of-plane magnetized layers. Initially, the determination of layer structure is explained, followed by the investigation of in-plane magnetic anisotropy. Later on, hysteresis loop shift measurements and current-induced magnetization switching are performed to characterize the SOT efficacy and field-free SOT switching performance, respectively. With the discovery of an unconventional hysteresis-like loop in SOT efficacy as a function of in-plane magnetic field (H_x), a built-in bias field is verified. In the angle-dependent measurements, a cosine function like behavior confirms the parallel relationship between the in-plane magnetization and the built-in bias field. After ruling out the potential mechanisms resulting in field-free SOT switching in this T-type structure, we shed light on the Ne ́el orange-peel effect. Also, the roughness-induced Ne ́el field (H_N) is estimated from surface topography using atomic force microscopy (AFM), which is then compared with the measured value from loop shift measurement. This acts as a bridge between measurement and calculation. Subsequently, devices are fabricated into pillars, in which field-free switching performance persists even after size shrinking. Additionally, other structure engineering like wedge structure and deposition with in-situ magnetic field are also demonstrated. Overall, this thesis provides a deeper insight into roughness-induced field-free mechanism along with the preliminary investigation into feasibility of scaling down.
Oral Examination Committee Approval i
Acknowledgement ii
摘要 iv
Abstract v
Contents vii
List of Figures x
List of Tables xvi
Chapter 1 Introduction 1
1.1 Magnetic Random Access Memory 1
1.2 Magnetic Anisotropy 2
1.2.1 In-Plane Magnetic Anisotropy 5
1.2.2 Perpendicular Magnetic Anisotropy 6
1.3 Transport Phenomena 9
1.3.1 Ordinary and Anomalous Hall Effect 9
1.3.2 Spin Hall Effect 12
1.4 Magnetization Dynamics 14
1.4.1 Landau-Lifshitz-Gilbert Equation 14
1.4.2 Spin-Transfer Torque and Spin-Orbit Torque 15
1.4.3 Domain Wall 18
1.5 Field-Free Spin-Orbit Torque Switching 18
1.5.1 Structure Engineering 19
1.5.2 Unconventional Spins 20
1.5.3 Built-in Bias Field 22
1.6 Motivation 23
Chapter 2 Sample Fabrication 25
2.1 Preparation Methods 25
2.1.1 Magnetron Sputtering 25
2.1.2 Photolithography 26
2.1.3 Ion Beam Etching 28
2.2 Preparation Flows 29
2.2.1 Hall Bar Devices 29
2.2.2 Pillar Devices 29
Chapter 3 Measurements 31
3.1 Magneto-Optical Kerr Effect 31
3.2 Hysteresis Loop Shift Measurement 33
3.3 Current-Induced Magnetization Switching 37
3.4 Atomic Force Microscopy 39
3.5 Summary of Experiments 40
Chapter 4 Performance in T-type CoFeB/W/CoFeB System 42
4.1 Structure Tuning 44
4.2 Determination of In-Plane Magnetic Anisotropy 46
4.3 Spin-Orbit Torque Characterization 47
4.3.1 Hysteresis Loop Shift Measurement 48
4.3.2 Current-Induced Magnetization Switching 52
4.3.3 Angle-Dependent Measurement 56
4.4 Discussion on Field-Free Mechanism 58
4.4.1 Exclusion of Other Potential Mechanisms 59
4.4.2 Ne ́el Orange-Peel Effect 62
4.5 Pillar Performance 65
4.6 Other Structure Engineering 68
Chapter 5 Summary 71
References 72
Appendix 79
K. Wang, J. Alzate, and P. K. Amiri, Low-power non-volatile spintronic memory: STT-RAM and beyond. J. Phys. D: Appl. Phys., 46, 074003 (2013).
D. Apalkov, A. Khvalkovskiy, S. Watts, V. Nikitin, X. Tang, D. Lottis, K. Moon, X. Luo, E. Chen, and A. Ong, Spin-transfer torque magnetic random access memory (STT-MRAM). ACM J. Emerg., 9, 1-35 (2013).
G. Prenat, K. Jabeur, G. Di Pendina, O. Boulle, and G. Gaudin, Beyond STT-MRAM, spin orbit torque RAM SOT-MRAM for high speed and high reliability applications. Spintronics-based Computing, 145-157 (2015).
M. Durlam, B. Craigo, M. DeHerrera, B. Engel, G. Grynkewich, B. Huang, J. Janesky, M. Martin, B. Martino, and J. Salter, in IEEE 2007 International Symposium on VLSI Technology, Systems and Applications (VLSI-TSA) (IEEE, 2007), pp. 1-2.
S. Ikeda, K. Miura, H. Yamamoto, K. Mizunuma, H. Gan, M. Endo, S. Kanai, J. Hayakawa, F. Matsukura, and H. Ohno, A perpendicular-anisotropy CoFeB–MgO magnetic tunnel junction. Nat. Mater., 9, 721-724 (2010).
L. Liu, C.-F. Pai, Y. Li, H. Tseng, D. Ralph, and R. Buhrman, Spin-torque switching with the giant spin Hall effect of tantalum. Science, 336, 555-558 (2012).
C.-F. Pai, L. Liu, Y. Li, H. Tseng, D. Ralph, and R. Buhrman, Spin transfer torque devices utilizing the giant spin Hall effect of tungsten. Appl. Phys. Lett., 101, 122404 (2012).
J. Dubowik, Shape anisotropy of magnetic heterostructures. Phys. Rev. B, 54, 1088 (1996).
C.-F. Pai and D. D. Tang, MAGNETIC MEMORY TECHNOLOGY: Spin-transfer-torque Mram and Beyond (John Wiley & Sons, 2020).
J. Finley and L. Liu, Spin-orbit-torque efficiency in compensated ferrimagnetic cobalt-terbium alloys. Phys. Rev. Appl., 6, 054001 (2016).
M. Johnson, P. Bloemen, F. Den Broeder, and J. De Vries, Magnetic anisotropy in metallic multilayers. Rep. Prog. Phys., 59, 1409 (1996).
P. Carcia, Perpendicular magnetic anisotropy in Pd/Co and Pt/Co thin‐film layered structures. J. Appl. Phys., 63, 5066-5073 (1988).
H. Yang, M. Chshiev, B. Dieny, J. Lee, A. Manchon, and K. Shin, First-principles investigation of the very large perpendicular magnetic anisotropy at Fe| MgO and Co| MgO interfaces. Phys. Rev. B, 84, 054401 (2011).
T. Miyajima, T. Ibusuki, S. Umehara, M. Sato, S. Eguchi, M. Tsukada, and Y. Kataoka, Transmission electron microscopy study on the crystallization and boron distribution of CoFeB/MgO/CoFeB magnetic tunnel junctions with various capping layers. Appl. Phys. Lett., 94, 122501 (2009).
E. H. Hall, On a new action of the magnet on electric currents. Am. J. Math. AM, 2, 287-292 (1879).
N. Nagaosa, J. Sinova, S. Onoda, A. H. MacDonald, and N. P. Ong, Anomalous hall effect. Rev. Mod. Phys., 82, 1539 (2010).
T. Tanaka, H. Kontani, M. Naito, T. Naito, D. S. Hirashima, K. Yamada, and J. Inoue, Intrinsic spin Hall effect and orbital Hall effect in 4 d and 5 d transition metals. Phys. Rev. B, 77, 165117 (2008).
M. Lakshmanan, The fascinating world of the Landau–Lifshitz–Gilbert equation: an overview. Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, 369, 1280-1300 (2011).
J. C. Slonczewski, Current-driven excitation of magnetic multilayers. J. Magn. Magn. Mater., 159, L1-L7 (1996).
L. Berger, Emission of spin waves by a magnetic multilayer traversed by a current. Phys. Rev. B, 54, 9353 (1996).
D. C. Ralph and M. D. Stiles, Spin transfer torques. J. Magn. Magn. Mater., 320, 1190-1216 (2008).
S. S. Parkin, C. Kaiser, A. Panchula, P. M. Rice, B. Hughes, M. Samant, and S.-H. Yang, Giant tunnelling magnetoresistance at room temperature with MgO (100) tunnel barriers. Nat. Mater., 3, 862-867 (2004).
D. D. Djayaprawira, K. Tsunekawa, M. Nagai, H. Maehara, S. Yamagata, N. Watanabe, S. Yuasa, Y. Suzuki, and K. Ando, 230% room-temperature magnetoresistance in CoFeB∕ MgO∕ CoFeB magnetic tunnel junctions. Appl. Phys. Lett., 86, 092502 (2005).
I. M. Miron, K. Garello, G. Gaudin, P.-J. Zermatten, M. V. Costache, S. Auffret, S. Bandiera, B. Rodmacq, A. Schuhl, and P. Gambardella, Perpendicular switching of a single ferromagnetic layer induced by in-plane current injection. Nature, 476, 189-193 (2011).
L. Liu, O. Lee, T. Gudmundsen, D. Ralph, and R. Buhrman, Current-induced switching of perpendicularly magnetized magnetic layers using spin torque from the spin Hall effect. Phys. Rev. Lett., 109, 096602 (2012).
Y. A. Bychkov and É. I. Rashba, Properties of a 2D electron gas with lifted spectral degeneracy. JETP lett, 39, 78 (1984).
I. Mihai Miron, G. Gaudin, S. Auffret, B. Rodmacq, A. Schuhl, S. Pizzini, J. Vogel, and P. Gambardella, Current-driven spin torque induced by the Rashba effect in a ferromagnetic metal layer. Nat. Mater., 9, 230-234 (2010).
O. Lee, L. Liu, C. Pai, Y. Li, H. Tseng, P. Gowtham, J. Park, D. Ralph, and R. Buhrman, Central role of domain wall depinning for perpendicular magnetization switching driven by spin torque from the spin Hall effect. Phys. Rev. B, 89, 024418 (2014).
S. Emori, E. Martinez, K.-J. Lee, H.-W. Lee, U. Bauer, S.-M. Ahn, P. Agrawal, D. C. Bono, and G. S. Beach, Spin Hall torque magnetometry of Dzyaloshinskii domain walls. Phys. Rev. B, 90, 184427 (2014).
G. Yu, P. Upadhyaya, Y. Fan, J. G. Alzate, W. Jiang, K. L. Wong, S. Takei, S. A. Bender, L.-T. Chang, and Y. Jiang, Switching of perpendicular magnetization by spin–orbit torques in the absence of external magnetic fields. Nat. Nanotechnol., 9, 548-554 (2014).
G. Yu, L.-T. Chang, M. Akyol, P. Upadhyaya, C. He, X. Li, K. L. Wong, P. K. Amiri, and K. L. Wang, Current-driven perpendicular magnetization switching in Ta/CoFeB/[TaOx or MgO/TaOx] films with lateral structural asymmetry. Appl. Phys. Lett., 105, 102411 (2014).
M. Akyol, G. Yu, K. Wong, and K. L. Wang, Current-driven magnetization switching under zero field in Pt/Ta (wedge)/CoFeB/MgO multilayers. Appl. Phys. Lett., 121, 112407 (2022).
T.-Y. Chen, H.-I. Chan, W.-B. Liao, and C.-F. Pai, Current-induced spin-orbit torque and field-free switching in Mo-based magnetic heterostructures. Phys. Rev. Appl., 10, 044038 (2018).
S. Zhang and Z. Li, Roles of nonequilibrium conduction electrons on the magnetization dynamics of ferromagnets. Phys. Rev. Lett., 93, 127204 (2004).
X. Shu, L. Liu, J. Zhou, W. Lin, Q. Xie, T. Zhao, C. Zhou, S. Chen, H. Wang, and J. Chai, Field-Free Switching of Perpendicular Magnetization Induced by Longitudinal Spin-Orbit-Torque Gradient. Phys. Rev. Appl., 17, 024031 (2022).
S.-h. C. Baek, V. P. Amin, Y.-W. Oh, G. Go, S.-J. Lee, G.-H. Lee, K.-J. Kim, M. D. Stiles, B.-G. Park, and K.-J. Lee, Spin currents and spin–orbit torques in ferromagnetic trilayers. Nat. Mater., 17, 509-513 (2018).
Y. W. Oh, J. Ryu, J. Kang, and B. G. Park, Material and thickness investigation in ferromagnet/Ta/CoFeB trilayers for enhancement of spin–orbit torque and field‐free switching. Adv. Electron. Mater., 5, 1900598 (2019).
L. Liu, C. Zhou, X. Shu, C. Li, T. Zhao, W. Lin, J. Deng, Q. Xie, S. Chen, and J. Zhou, Symmetry-dependent field-free switching of perpendicular magnetization. Nat. Nanotechnol., 16, 277-282 (2021).
L. Liu, Q. Qin, W. Lin, C. Li, Q. Xie, S. He, X. Shu, C. Zhou, Z. Lim, and J. Yu, Current-induced magnetization switching in all-oxide heterostructures. Nat. Nanotechnol., 14, 939-944 (2019).
C. O. Avci, C.-H. Lambert, G. Sala, and P. Gambardella, Chiral coupling between magnetic layers with orthogonal magnetization. Phys. Rev. Lett., 127, 167202 (2021).
Y.-H. Huang, C.-C. Huang, W.-B. Liao, T.-Y. Chen, and C.-F. Pai, Growth-Dependent Interlayer Chiral Exchange and Field-Free Switching. Phys. Rev. Appl., 18, 034046 (2022).
S. Fukami, C. Zhang, S. DuttaGupta, A. Kurenkov, and H. Ohno, Magnetization switching by spin–orbit torque in an antiferromagnet–ferromagnet bilayer system. Nat. Mater., 15, 535-541 (2016).
K. Garello, F. Yasin, H. Hody, S. Couet, L. Souriau, S. H. Sharifi, J. Swerts, R. Carpenter, S. Rao, and W. Kim, in IEEE Symposium on VLSI Circuits (IEEE, Kyoto, 2019), pp. T194-T195.
V. Krizakova, K. Garello, E. Grimaldi, G. S. Kar, and P. Gambardella, Field-free switching of magnetic tunnel junctions driven by spin–orbit torques at sub-ns timescales. Appl. Phys. Lett., 116, 232406 (2020).
Y. Liu, B. Zhou, Z. Dai, E. Zhang, and J.-G. Zhu, Iridium Enabled Field-free Spin-orbit Torque Switching of Perpendicular Magnetic Tunnel Junction Device. arXiv:1911.05007, (2019).
P. Williams, Secondary ion mass spectrometry. Annual Review of Materials Science, 15, 517-548 (1985).
D. Allwood, G. Xiong, M. Cooke, and R. Cowburn, Magneto-optical Kerr effect analysis of magnetic nanostructures. J. Phys. D: Appl. Phys., 36, 2175 (2003).
S. Emori, U. Bauer, S.-M. Ahn, E. Martinez, and G. S. Beach, Current-driven dynamics of chiral ferromagnetic domain walls. Nat. Mater., 12, 611-616 (2013).
C.-F. Pai, M. Mann, A. J. Tan, and G. S. Beach, Determination of spin torque efficiencies in heterostructures with perpendicular magnetic anisotropy. Phys. Rev. B, 93, 144409 (2016).
A. Thiaville, S. Rohart, É. Jué, V. Cros, and A. Fert, Dynamics of Dzyaloshinskii domain walls in ultrathin magnetic films. Europhysics Letters, 100, 57002 (2012).
T.-Y. Chen, W.-B. Liao, T.-Y. Chen, T.-Y. Tsai, C.-W. Peng, and C.-F. Pai, Current-induced spin–orbit torque efficiencies in W/Pt/Co/Pt heterostructures. Appl. Phys. Lett., 116, 072405 (2020).
R. Koch, J. Katine, and J. Sun, Time-resolved reversal of spin-transfer switching in a nanomagnet. Phys. Rev. Lett., 92, 088302 (2004).
W.-B. Liao, T.-Y. Chen, Y.-C. Hsiao, and C.-F. Pai, Pulse-width and temperature dependence of memristive spin–orbit torque switching. Appl. Phys. Lett., 117, 182402 (2020).
F. J. Giessibl, Advances in atomic force microscopy. Rev. Mod. Phys., 75, 949 (2003).
M. Chang, J. Yun, Y. Zhai, B. Cui, Y. Zuo, G. Yu, and L. Xi, Field free magnetization switching in perpendicularly magnetized Pt/Co/FeNi/Ta structure by spin orbit torque. Appl. Phys. Lett., 117, 142404 (2020).
Y. Sheng, K. W. Edmonds, X. Ma, H. Zheng, and K. Wang, Adjustable Current‐Induced Magnetization Switching Utilizing Interlayer Exchange Coupling. Adv. Electron. Mater., 4, 1800224 (2018).
Y.-C. Lau, D. Betto, K. Rode, J. Coey, and P. Stamenov, Spin–orbit torque switching without an external field using interlayer exchange coupling. Nat. Nanotechnol., 11, 758-762 (2016).
N. Murray, W.-B. Liao, T.-C. Wang, L.-J. Chang, L.-Z. Tsai, T.-Y. Tsai, S.-F. Lee, and C.-F. Pai, Field-free spin-orbit torque switching through domain wall motion. Phys. Rev. B, 100, 104441 (2019).
W. Yang, Z. Yan, Y. Xing, C. Cheng, C. Guo, X. Luo, M. Zhao, G. Yu, C. Wan, and M. Stebliy, Role of an in-plane ferromagnet in a T-type structure for field-free magnetization switching. Appl. Phys. Lett., 120, 122402 (2022).
W. Chen, L. Qian, and G. Xiao, Deterministic current induced magnetic switching without external field using giant spin Hall effect of β-W. Sci. Rep., 8, 1-8 (2018).
J. Kools, W. Kula, D. Mauri, and T. Lin, Effect of finite magnetic film thickness on Néel coupling in spin valves. J. Appl. Phys., 85, 4466-4468 (1999).
B. Schrag, A. Anguelouch, S. Ingvarsson, G. Xiao, Y. Lu, P. Trouilloud, A. Gupta, R. Wanner, W. Gallagher, and P. Rice, Néel “orange-peel” coupling in magnetic tunneling junction devices. Appl. Phys. Lett., 77, 2373-2375 (2000).
J. W. Chenchen, M. A. K. B. Akhtar, R. Sbiaa, M. Hao, L. Y. H. Sunny, W. S. Kai, L. Ping, P. Carlberg, and A. K. S. Arthur, Size dependence effect in MgO-based CoFeB tunnel junctions with perpendicular magnetic anisotropy. Jpn. J. Appl. Phys., 51, 013101 (2011).
W. Stefanowicz, L. Nistor, S. Pizzini, W. Kuch, L. Buda-Prejbeanu, G. Gaudin, S. Auffret, B. Rodmacq, and J. Vogel, Size dependence of magnetic switching in perpendicularly magnetized MgO/Co/Pt pillars close to the spin reorientation transition. Appl. Phys. Lett., 104, 012404 (2014).
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