DGIST Scholar: The Spin Dynamics Study on the Various Heavy metal/Ferromagnet Thin FilMaster with Strong Spin-Orbit Coupling : Asymmetric Exchange Interaction, Magnetic Anisotropy, Magnetic Damping

Department of Physics and Chemistry Theses Ph.D.

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The Spin Dynamics Study on the Various Heavy metal/Ferromagnet Thin FilMaster with Strong Spin-Orbit Coupling : Asymmetric Exchange Interaction, Magnetic Anisotropy, Magnetic Damping

Title: The Spin Dynamics Study on the Various Heavy metal/Ferromagnet Thin FilMaster with Strong Spin-Orbit Coupling
: Asymmetric Exchange Interaction, Magnetic Anisotropy, Magnetic Damping

Author(s): Nam-Hui Kim

DGIST Authors: Kim, June-Seo ; Kim, Nam-Hui ; You, Chun Yeol

Advisor: 유천열

Co-Advisor(s): June-Seo Kim

Issued Date: 2019

Awarded Date: 2019-08

Type: Thesis

Description: Interfacial Dzyaloshinskii-Moriya interaction (iDMI), Perpendicular magnetic anisotropy (PMA), Gilbert damping constant, Slater-Pauling curve, Brillouin light scattering (BLS), Ferromagnetic resonance (FMR)

Table Of Contents: Ⅰ. INTRODUCTION 16
Ⅱ. THEORETICAL BACKGROUND 19
2.1 Zeeman energy 19
2.2 Exchange energy 19
2.3 Magnetic crystalline anisotropy energy 20
2.4.Shape anisotropy energy 22
2.5 Spin orbit coupling (SOC) 22
2.6 Perpendicular magnetic anisotropy (PMA) 24
2.7 Dzyaloshinskii-Moriya interaction (DMI) 25
2.8 Magnetization dynamics 26
2.8.1 Spin wave 27
2.8.2 Landau-Lifshitz-Gilbert equation (LLG equation) 28
2.9 Slater-Pauling curve 30
Ⅲ. EXPERIMENTAL APPRATUS 33
3.1 Brillouin Light Scattering (BLS) 33
3.1.1 Inelastic scattering 35
3.1.2 (3+3) Multi-pass tandem Fabry–Pérot interferometer (FPI) 37
3.2 Ferromagnetic resonance (FMR) 43
Ⅳ. EXPERIMENTAL RESULT 47
4.1 Enhancement of Dzyaloshinskii-Moriya interaction by using Ta buffer layer 47
4.1.1 Overview 47
4.1.2 Sample fabrication and measurement 47
4.1.3 Result and Discussion 49
4.1.4 Summary 54
4.2 Interfacial Dzyaloshinskii-Moriya interaction, surface anisotropy, and spin pumping at spin orbit coupled Ir/Co structure 56
4.2.1 Overview 56
4.2.2 Sample fabrication and measurement 57
4.2.3 Result and Discussion 58
4.2.4 Summary 67
4.3 Role of top and bottom interfaces of a Pt/Co/AlO x structure in Dzyaloshinskii-Moriya interaction, interfacial magnetic anisotropy, and Magneto-optical Kerr effect 68
4.3.1 Overview 68
4.3.2 Sample fabrication and measurement 68
4.3.3 Result and Discussion 70
4.3.4 Summary 81
4.4 Dependence of interfacial Dzyaloshinskii-Moriya interaction and perpendicular magnetic anisotropy on the thickness of the heavy-metal layer 83
4.4.1 Overview 83
4.4.2 Sample fabrication and measurement 83
4.4.3 Result and Discussion 85
4.4.5 Summary 94
4.5 Investigation of magnetic properties at 3d transition materials including magnetic moment, interfacial Dzyaloshinskii-Moriya interaction, surface anisotropy, and damping coefficient showing tendency of the Slater-Pauling curve 95
4.5.1 Overview 95
4.5.2 Sample fabrication and measurement 96
4.5.3 Result and Discussion 98
4.5.4 Summary 119
Ⅴ. CONCLUSION 120
Ⅵ. REFERENCES 123