Contents
1 Introduction 1
References 3
2 Electron Shell Structure of Free Atoms and Valence Electrons in Crystals 5
2.1 Electron Shell Structure of Free Atoms 5
2.2 A Simple Introduction to Classical Crystal Binding Theory for Typical Magnetic Materials 6
2.3 Effective Radii of Ions in Crystals 8
2.4 Electron Binding Energy Originating from Ions in Crystals 9
References 11
3 A Simple Introduction to Basic Knowledge of Magnetic Materials 13
3.1 Classification of Matter Based on Magnetic Properties 13
3.2 Magnetic Domain and Domain Wall 16
3.3 Basic Parameters of Magnetic Materials 18
3.4 Magnetic Ordering Models in Conventional Ferromagnetism 21
References 24
4 Difficulties Faced by Conventional Magnetic Ordering Models 25
4.1 Disputes Over the Cation Distributions in Mn and Cr Spinel Ferrites 25
4.1.1 Normal， Inverse， and Mixed Spinel Structure 25
4.1.2 Magnetic Moments of 3d Transition Metal Ions 27
4.1.3 Magnetic Ordering of CrFe204 and MnFe204 27
4.2 Difficulties in Describing the Observed Magnetic Moments of Perovskite Manganites 31
4.3 Relationship Between Magnetic Moment and Resistivity in Typical Magnetic Metals 38
4.4 Puzzle for the Origin of Magnetic Ordering Energy 38
References 39
5 02p Itinerant Electron Model for Magnetic Oxides 43
5.1 A Simple Introduction to Early Investigations of Ionicity 43
5.2 Study of the Ionicity of Spinel Ferrites 45
5.2.1 Quantum-Mechanical Potential Barrier Model Used to Estimate Cation Distributions 46
5.2.2 Study of the Ionicity of Group II-VI Compounds Using the Quantum-Mechanical Potential Barrier Model 47
5.2.3 Study of Ionicity of Spinel Ferrite Fe3o4 48
5.2.4 Estimation of the Ionicity of Spinel Ferrites M3O4 Using the Quantum- Mechanical Potential Barrier Model 50
5.3 Experimental Studies of O 2p Holes in Oxides 51
5.3.1 O 2p Hole Studies Using Electron Energy Loss Spectroscopy 52
5.3.2 Several Other Experimental Investigations for O 2p Holes 54
5.4 Study of Negative Monovalent Oxygen Ions Using X-Ray Photoelectron Spectra 54
5.4.1 Study of Ionicity of BaTiC>3 and Several Monoxides Using O Is XPS 55
5.4.2 Effect of Argon Ion Etching on the O Is Photoelectron Spectra of SrTio3 60
5.5 O 2p Itinerant Electron Model for Magnetic Oxides (IEO Model) 70
5.6 Relationship Between the IEO Model and the Conventional Models 75
References 79
6 Magnetic Ordering of Typical Spinel Ferrites 81
6.1 Method Fitting Magnetic Moments of Typical Spinel Ferrites 81
6.1.1 X-ray Diffraction Analysis 82
6.1.2 Magnetic Property Measurements 84
6.1.3 Primary Factors that Affect Cation Distributions 85
6.1.4 Fitting the Magnetic Moments of the Samples 88
6.1.5 Discussion on Cation Distributions 91
6.2 Cation Distribution Characteristics in Typical Spinel Ferrites 94
References 100
7 Experimental Evidences of the IEO Model Obtained from Spinel Ferrites 101
7.1 Additional Antiferromagnetic Phase in Ti-Doped Spinel Ferrites 101
7.1.1 X-ray Diffraction Spectra of the Samples 102
7.1.2 X-ray Energy Dispersive Spectra of the Samples 104
7.1.3 Magnetic Measurements and Analysis of the Results 106
7.1.4 Cation Distributions of the Three Series of Ti-Doped Samples 108
7.1.5 Magnetic Ordering of Spinel Ferrites TicM1_xFe204 (M = Co， Mn) 115
7.2 Amplification of Spinel Ferrite Magnetic Moment Due to Cu Substituting for Cr 116
7.2.1 X-ray Energy Dispersive Spectrum Analysis 116
7.2.2 X-ray Diffraction Analysis 117
7.2.3 Magnetic Measurement and Magnetic Moment Fitting Results 118
7.3 Unusual Infrared Spectra of Cr Ferrite 122
7.3.1 Infrared Spectra of Spinel Ferrites M￥q2Oa (M=Fe， Co， Ni， Cu， Cr) 123
7.3.2 Dependency of the Peak Position V2 on the Magnetic Moment (/Xm2) of Divalent M Cations in MFe2O4(M= Fe， Co， Ni， Cu， Cr) 125
7.3.3 Infrared Spectra of and CoCrxFe2-x04 126
References 126
8 Spinel Ferrites with Canted Magnetic Coupling 129
8.1 Spinel Ferrites with Fe Ratio Being Less Than 2.0 Per Molecule 129
8.2 Spinel Ferrites Containing Nonmagnetic Cations 132
8.2.1 Disputation of Nonmagnetic Cation Distribution 133
8.2.2 Fitting Sample Magnetic Moments 136
8.2.3 Discussion on Cation Distributions 137
References 145
9 Magnetic Ordering and Electrical Transport of Perovskite Manganites 147
9.1 Ferromagnetic and Antiferromagnetic Coupling in Typical Perovskite Manganites 147
9.1.1 Crystal Structure and Magnetic Measurement Results of Lai-xSrxMnOs Polycrystalline Powder Samples 147
9.1.2 Study of Valence and Ionicity of Lai-xSrxMn03 150
9.1.3 Fitting of the Curve of the Magnetic Moment Versus Sr Ratio for Lai-xSrxMn03 152
9.2 Spin-Dependent and Spin-Independent Electrical Transport of Perovskite Manganites 155
9.2.1 A Model with Two Channels of Electrical Transport for ABO3 Perovskite Manganites 156
9.2.2 Fitting the Curves of Resistivity Versus Test Temperature o
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