Title

Spin Torque Majority Gate with Magnetic Domain Wall Inverter for Next-Generation Spintronic Logic Applications

Alternative Title

차세대 스핀트로닉스 논리 소자 응용을 위한 자구벽 인버터를 갖춘 스핀 토크 다수결 게이트

DGIST Authors

Sunghyun Min ; Chun-Yeol You ; June-Seo Kim

Advisor

유천열

Co-Advisor(s)

June-Seo Kim

Issued Date

2026

Awarded Date

2026-02-01

Type

Thesis

Description

Ruderman-Kittel-Kasuya-Yosida (RKKY) Interaction, Domain Wall (DW), Spin Orbit Torque (SOT), Field Free Switching, Perpendicular Magnetic Anisotropy (PMA)

Table Of Contents

Ⅰ. Introduction 1
Ⅱ. Theoretical backgrounds 5
2.1 Basic concepts of spintronics 6
2.1.1 Magnetic moment 7
2.1.2 Spin orbit coupling 9
2.1.3 Exchange interaction 11
2.1.3.1 Dzyaloshinskii-Moriya interaction 13
2.1.3.2 Interlayer exchange coupling and RKKY interaction 15
2.1.3.3 Superlattice in magnetic thin films 17
2.1.4 Magnetic anisotropy energy and magnetic hysteresis loop 19
2.1.4.1 Magnetocrystalline anisotropy 21
2.1.4.2 Shape magnetic anisotropy 23
2.1.4.3 Perpendicular magnetic anisotropy 24
2.1.4.4 L10 ordering 26
2.2 Magnetic domain wall and related interactions 28
2.3 Spin torque mechanisms 29
2.3.1 Landau-Lifshitz-Gilbert equation 30
2.3.2 Spin Hall effect 31
2.3.3 Spin orbit torque and field free switching 32
2.4 Processing in memory devices and spintronic logic applications 33
2.4.1 Spin torque majority gate 35
2.4.1.1 Conventional architecture 39
2.4.1.2 New architecture 42
2.4.2 Magnetic domain wall inverter 46
Ⅲ. Fabrication process and Experimental tools 51
3.1 Fabrication process flows by device architecture 52
3.1.1 Fabrication process for the conventional architecture 52
3.1.2 Fabrication process for the improved new architecture 53
3.1.3 Fabrication process for three-dimensional domain wall inverter 54
3.2 Sample fabrication process 56
3.2.1 Magnetic multilayer deposition technique 56
3.2.2 Lithography techniques 61
3.2.2.1 Electron beam lithography technique 63
3.2.2.2 Photolithography technique 68
3.2.3 Etching techniques 70
3.2.3.1 Reactive ion etching technique 71
3.2.3.2 Ion beam etching technique 72
3.2.4 Passivation techniques 75
3.2.4.1 Plasma enhanced atomic layer deposition technique 75
3.2.4.2 Plasma enhanced chemical vapor deposition technique 77
3.2.5 Annealing technique 80
3.3 Nano materials analysis and characterization 83
3.3.1 Structure imaging techniques 83
3.3.1.1 Field emission scanning electron microscope measurements 83
3.3.1.2 Optical microscope measurements 85
3.3.2 Surface analysis 86
3.3.2.1 Atomic force microscope measurements 86
3.3.3 Magnetic thin film analysis 88
3.3.3.1 Magneto-optical Kerr effect measurements 88
Ⅳ. Result and Discussion 96
4.1 Spin torque majority gate device 97
4.1.1 Compositional analysis of CMOS passivation layer 97
4.1.2 Design and deposition of STMG device magnetic thin-film stack 98
4.1.3 Current density distribution in conventional architecture 99
4.1.4 Conventional architecture-based STMG device fabrication 101
4.1.5 Current density distribution in the improved new architecture 104
4.1.6 Improved new architecture-based STMG device fabrication 105
4.1.7 Integration with CMOS devices 108
4.1.8 Electrical characterization and magnetic signal detection 111
4.2 Synthetic antiferromagnet-based domain wall motion inverter device 113
4.2.1 Magnetic property comparison between the SAF and the top layer 114
4.2.2 PMA optimization through top Ta buffer layer 116
4.2.3 Engineering PMA in the top ferromagnet layer 119
4.2.4 Engineering PMA in the bottom ferromagnet layer 122
4.2.5 Planarization technology using the lift-off process 125
4.2.6 Verification of magnetic properties in patterned SAF structures 131
Ⅴ. Conclusion 133
Ⅵ. References 136

URI

https://scholar.dgist.ac.kr/handle/20.500.11750/59740
http://dgist.dcollection.net/common/orgView/200000947269

DOI

10.22677/THESIS.200000947269

Degree

Master

Department

Department of Physics and Chemistry

Publisher

DGIST

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