The density functional studies on the electonics structures and magnetism of surfaces and interfaces of the transition metal compounds : 전이금속 화합물 표면 및 계면의 전자구조와 자성에 대한 밀도범함수이론 연구

다국어 초록 (Multilingual Abstract)

Electronic structures and magnetism of surfaces and interfaces, as well as some non-oxide perovskite bulk, of various transition metal compounds are investigated in terms of density functional theory (DET) by using the all-electron full-potential linearized augmented plane wave (FLAPW) method. DFT, as a method to solve the solid state many-body problem, is reviewed.
The all-electron FLAPW method is also reviewed, with arguments of symme-tries in solids. Since its importance of work function on surface sciences, the work function of the high-index copper surfaces is calculated and discussed its variation along the change of surface index, and alkali metal adsorption on transition metal surfaces as is an example of work function lowering, as well as the effects on the interface magnetism. Surface and interface magnetism of transition metals and transition metal compounds, which are important in spintronics applications, are investigated also. First of all, magnetism of stepped nickel surfaces is investigated and then magnetism of the iron nitride surfaces is presented. Fe/Cr system as as a prototype of giant magentoresis-tance materials is calculated and discussed with the results of X-ray magnetic circular dichroism. NiPd thin film on Cu3Au substrates, as is a candidate of tailored overlayer magnetic thin films by varying the composition and sub-strates, is also studied. The properties of magnetism in Fe/B2-FeSi(001) are investigated also. Newly discovered superconductor MgB2 surface electronic structures are also studied. The nonoxide perovskite MgCNi_(3), a new kind of superconductors, is studied on the effects of d-band hole doping, and then its surface electronic structure is also investigated. The first-order magnetic phase transition in GaCMn_(3), another nonoxide perovskite, is investigated in terms of spin density inversion symmetry. Finally, conclusion and future aspects of the computational solid state physics are discussed briefly.

국문 초록 (Abstract)

다양한 전이금속 화합물의 표면과 계면의 전자구조와 자성을 밀도범함수 이론의 전전자 총에너지 총퍼텐셜 선형 보강 평면파 (FLAPW: full-potential linearized augmented plane wave) 방법을 이용하여 연구하였다. 고체의 다체 문제를 풀기 위한 한가지 방법으로서의 밀도범함수 이론을 살펴보았다. 전 전자 FLAPW방법을 고체의 대칭성에 대한 논의과 함께 살펴보았다. 표면과학에서 일함수의 중요성을 강조하기 위해, 높은 지수의 구리 표면에서의
일함수를 계산하고 표면 지수에 따른 변화를 토의 하였다. 그리고 일함수 강하의 예로서 알칼리 금속이 얹혀진 전이금속 표면 등에 대하여 탐구하였다.
스핀트로닉스 응용에 있어 중요한 전이금속 및 전이금속 화합물의 표면 및 계면 자설에 대해서도 연구하였다. 먼저, 계단이 형성된 니켈 표면의 자성을 탐구한 후, 질소화철 표면의 자성을 살펴보았다. 거대 자기저항 효과의 대표 물질인 Fe/Cr계와 박막에서의 웃층 자성을 X-선 자기원 이색성과 함께 연구하였다. 조성비와 기판을 변화시켜 재단할 수 있는 Cu_(3)Au표면 위의 NiPd 웃층계도 연구하였다. 새로운 스핀트로닉스 물질로서의 Fe/B2-FeSi계의 자성도 연구하였다. 새로이 발견된 초전도체인 MgB_(2)의 표면 전자구조
에 대해서 연구하였다. 다른 종류의 초전도체인 비산화 페롭스카이트 구조의 MgCNi_(3)의 d띠 흘 첨가의 효과를 연구하고, 그 표면의 전자구조에 대해서도 탐구하였다. 또다른 비산화 페롭스카이트 구조를 갖는 CaCMn_(3)의 1차 자성 전이를 스핀밀도-공간역전 대칭성을 통하여 연구하였다. 마지막으로, 결론을 맺고 전산 고체물리학의 미래에 대해서 간략하게 설명하였다.

목차 (Table of Contents)

• Abstract = i
• Contents = iii
• List of Tables = vii
• List of Figures = ix
• 1 Introduction = 1
• 1.1 Many-electron Systems = 2
• 1.2 Choosing Basis Functions = 4
• 1.3 Theseopes:Sorfacesandlnterfaces = 8
• 2 The Density Functional Formalism as a Many-Body Theory = 12
• 2.1 The Adiabatic Approximation = 13
• 2.2 The Density Functional Formalism = 15
• 2.3 The Kohn-Sham Equation = 17
• 2.4 The Local Density Approximation = 20
• 2.4.1 A Derivation of the Local Density Approximation = 20
• 2.4.2 The Explicit Local Exchange-Correlation Potentials = 23
• 2.5 The local Spin Density Approximation = 25
• 2.6 The Generalized Gradient Approximation = 30
• 2.7 TreatmentsofRelativisticEffectsintheDFT = 34
• 3 The Full-potential Linearized Augmented Plane Wave Method = 37
• 3.1 Symmetries in solids = 37
• 3.1.1 Translational Symmetry Bloch's Theorem = 39
• 3.1.2 The Reciprocal attice and Brillouin Zones = 41
• 3.1.3 Rotational Symmetry: Stars = 42
• 3.1.4 Time-Reversal symmetry = 43
• 3.2 The Linearized APW Function = 44
• 3.2.1 The Augmented Plane Wave Method = 45
• 3.2.2 The Linearized APW Basis = 48
• 3.3 The Film LAPW method = 49
• 3.4 The Non-spherical Potential in the LAPW method: The FLAPW Method = 53
• 3.4.1 Solution of Poisson's Equation = 53
• 3.4.2 The Total Potential and the Non-spherical Hamiltonian Matrix Elements = 56
• 4. Work Functions and Work Function Reduction by Alkali Metal Adsorption = 58
• 4.1 Work Functions of the High-Index Cu Surfaces = 60
• 4.1.1 Introduction = 60
• 4.1.2 Methods = 62
• 4.1.3 Results and Discussions = 63
• 4.1.4 Summary = 68
• 4.2 Electronic Structures of Na/Ta(110) Surfaces = 69
• 4.2.1 Introduction = 69
• 4.2.2 Theoretical Modelling and Computational Aspects = 72
• 4.2.3 Results and Discussions = 73
• 4.2.4 Summary = 78
• 4.3 Interface Magnetism and Electronic Structures of K/Fe(110) = 78
• 5 Surface and Interface Magnetism of Transition Metal Com- pounds = 83
• 5.1 Magnetism of Stepped Ni(001)Surface = 85
• 5.1.1 Introduction = 85
• 5.1.2 Calculational Methods = 87
• 5.1.3 Results and Discussions = 89
• 5.1.4 Summary = 96
• 5.2 Surface Magnetism of fe4N(001) = 97
• 5.2.1 Introduction = 97
• 5.2.2 Method of calculation = 99
• 5.2.3 Results and Discussions = 101
• 5.2.4Summary = 108
• 5.3 Surface and Interface Magnetism of Fe/Cr System = 109
• 5.3.1 Introduction = 109
• 5.3.2 Calculational Methods = 111
• 5.3.3 Results and Discussions = 112
• 5.3.4 Summary = 116
• 5.4 X-ray Magnetic Circular Dichroism Spectra of Fe/cr(001) = 116
• 5.4.1 Introduction = 116
• 5.4.2 Calculational Methods = 119
• 5.4.3 Results and Discussions = 121
• 5.4.4 Conclusions = 124
• 5.5 Site Dependence of NiPd Overlayer Magnetism on Cu3Au(001) = 12
• 5.6 Overlayer Magnetism of Fe/B2-FeSi(001) = 132
• 6 Surfaces of Superconductors and Their Magnetic Variants = 137
• 6.1 Surface Electronic Structures of a New Kind Superconductor MgB2(0001) = 138
• 6.2 Effects of d-band Hole Doping on Electronic Structure, Mag-netism, and Superconductivity in MgCNi3 = 148
• 6.2.1 Introduction = 148
• 6.2.2 Calculational Method = 149
• 6.2.3 Results and Discussions = 151
• 6.2.4 Summary = 159
• 6.3 Surface Electronic Structure of Superconducting MgCNi3(001) = 159
• 6.3.1 Introduction = 159
• 6.3.2 Calculational Method = 161
• 6.3.3 Results and Discussion = 162
• 6.3.4 Summary = 172
• 6.4 Spin Density Inversion Symmetry Driven First-Order Magnetic phase Transition in GaCMn3 = 173
• 7 Conclusive summary = 184
• 7.1 Summary of the Thesis = 184
• 7.2 Prospects = 187
• Summary(in korean) = 192
• References = 193