Title

Field-free magnetization switching in unconventional Hall bar system

Alternative Title

특수한 홀 바 시스템을 사용한 무-자기장 자화 스위칭 관찰

DGIST Authors

Hyeong-Joo Seo ; Chun-Yeol You ; Jung-Il Hong

Advisor

유천열

Co-Advisor(s)

Jung-Il Hong

Issued Date

2023

Awarded Date

2023-02-01

Citation

Hyeong-Joo Seo. (2023). Field-free magnetization switching in unconventional Hall bar system. doi: 10.22677/THESIS.200000652296

Type

Thesis

Description

Spin-orbit torque, Field-free magnetization switching, DMI, non-uniform current density, Oersted field, 수직 자기 이방성, 스핀 궤도 토크, DM 상호작용, Oersted 자기장, 무자기장 스위칭

Table Of Contents

I. Introduction 1
II. Theoretical background 3
2.1 Spin-orbit torque 3
2.1.1 Spin-transfer torque (STT) and spin-orbit torque (SOT) magnetization switching 4
2.1.2 Field-free magnetization switching 4
2.2 Dzyaloshinskii-Moriya interaction 5
2.3 Electrical measurement based on anomalous Hall effect 7
III. Materials & Methods 8
3.1 Sample preparation 8
3.1.1 Magnetron Sputtering 8
3.1.2 Photolithography 10
3.1.3 Ion beam milling 11
3.2 Magnetic property measurement 12
3.2.1 Vibrational Sample Magnetometer (VSM) 12
3.2.2 Generalized Sucksmith-Thompson (GST) method 13
3.2.3 Brillouin light scattering (BLS) spectroscopy 14
3.3 Magnetization switching measurement 16
3.3.1 SOT induced magnetization switching measurement 16
3.3.2 External out-of-plane field induced magnetization switching measurement 16
3.4 Magneto-optic Kerr microscope (MOKE) 17
IV. Results and discussion 18
4.1 Sample geometry 18
4.2 Magnetic properties 20
4.3 Field-free & Field-assisted magnetization switching via electrical measurement 22
4.4 Magnetization switching measurement via Kerr microcope 24
4.5 Perpendicular external field induced magnetization switching measurement 26
4.6 Verifying the origin of field-free magnetization switching in our experiment 30
4.6.1 Non-uniform current density distribution 30
4.6.2 Tilted magnetization at edge of the structure (DMI) 32
4.6.3 Oersted field 34
V. Conclusion 37
VI. References 38

URI

http://hdl.handle.net/20.500.11750/45774
http://dgist.dcollection.net/common/orgView/200000652296

DOI

10.22677/THESIS.200000652296

Degree

Master

Department

Department of Physics and Chemistry

Publisher

DGIST

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