Nano-Characterization of Co-Cr-P-Pt Magnetic thin Films for Magnetic Recording

다국어 초록 (Multilingual Abstract)

In the present study, four sets of Co-Cr-P-Pt magnetic thin films were investigated in order to understand the effect of phosphorus and platinum on the alloy system. The main part of this study was to understand the effect of each element on the alloy and to investigate the microstructural features. The foremost feature, the compositional distribution in the Co-Cr-P-Pt thin films, was investigated as a function of phosphorus and platinum addition. The addition of 4-6 at. % P and 11-13 at. % Pt showed significant improvements in coercivity. This was caused by the segregation of Cr. Modulation of the other element was observed and had direct relationship with the segregation of Cr. The segregation of the non-magnetic phase caused an increase in coercivity. The average grain size, shape, physical separations, and crystallographic orientation relation were investigated. Phosphorus increased the in-plane orientation while decreasing the Co (002). Meanwhile, the addition of Pt decreased the in-plane orientation resulting in a random orientation that promoted magnetic isolation between grains. The changes in inplane orientation affected the noise characteristics. Transmission electron microscopy was used to examine the microstructures of a magnetic layer. Electron energy loss spectroscopy in conjunction with energy dispersive x-ray spectroscopy was also used.

목차 (Table of Contents)

• ABSTRACT = ⅱ
• ACKNOWLEDGMENTS = ⅲ
• TABLE OF CONTENTS = ⅳ
• LIST OF TABLES = ⅶ
• LIST OF FIGURES = ⅷ
• Chapter 1 INTRODUCTION = 1
• 1.1 MAGNETIC HARD DISK TECHNOLOGY = 2
• 1.1.1 History of hard disk drive = 2
• 1.1.2 Developments of alloy thin films = 3
• 1.1.3 Structure and processing conditions = 5
• 1.1.4 Characteristics of high-density magnetic thin film = 8
• 1.2 THEORETICAL BACKGROUND = 14
• 1.2.1 Magnetocrystalline anisotropy = 17
• 1.2.2 Shape anisotropy = 18
• 1.2.3 Magnetization process = 19
• 1.2.4 Magnetic interactions = 22
• 1.3 SCOPE OF THIS STUDY = 25
• Chapter 2 METHODOLOGY = 26
• 2.1 EXPERIMENTAL TECHNIQUES = 26
• 2.1.1 Transmission electron microscope (TEM) = 26
• 2.1.2 Energy dispersive x-ray spectroscopy (EDS) = 28
• 2.1.3 Electron energy loss spectroscopy (EELS) = 29
• 2.1.4 Energy filtered imaging (EFI) = 30
• 2.2 EXPERIMENTAL PROCEDURE = 38
• 2.2.1 Sample fabrication = 38
• 2.2.2 Sample preparation = 39
• 2.2.3 Microstructural characterization = 40
• 2.2.4 Computer simulation of electron microscopy = 45
• 2.3 MICROSTRUCTURAL FEATURES = 50
• 2.3.1 Effect of Cr underlayer = 51
• 2.3.2 Physical separation = 52
• 2.3.3 Orientation relationship = 53
• 2.3.4 Compositional segregation = 54
• 2.3.5 Magnetic interactions = 54
• 2.3.6 Thin film media noise = 55
• Chapter 3 RESULT AND DISCUSSION = 57
• 3.1 MICROSTRUCTURE = 59
• 3.1.1 Effect of Cr underlayer thickness and texture = 59
• 3.1.2 The grain size and shape = 64
• 3.1.3 Physical separation of grains = 69
• 3.1.4 Crystallography and orientation relationship = 73
• 3.1.5 The compositional segregation = 79
• 3.2 EFFECT OF P ADDITION = 85
• 3.2.1 Morphology = 85
• 3.2.2 Crystallography = 89
• 3.2.3 Microchemistry = 94
• 3.3 EFFECT OF PT ADDITION = 102
• 3.3.1 Morphology = 104
• 3.3.2 Crystallography = 108
• 3.3.3 Microchemistry = 116
• Chapter 4 SUMMARY = 124
• Chapter 5 RECOMMENDATIONS = 127
• LITERATURE CITED = 129