Physics of Magnetic Nanostructures

A comprehensive coverage of the physical properties and real-world applications of magnetic nanostructures

This book discusses how the important properties of materials such as the cohesive energy, and the electronic and vibrational structures are affected when materials have at least one length in the nanometer range. The author uses relatively simple models of the solid state to explain why these changes in the size and dimension in the nanometer regime occur. The text also reviews the physics of magnetism and experimental methods of measuring magnetic properties necessary to understanding how nanosizing affects magnetism. Various kinds of magnetic structures are presented by the author in order to explain how nanosizing influences their magnetic properties. The book also presents potential and actual applications of nanomaterials in the fields of medicine and computer data storage.

 Physics of Magnetic Nanostructures:

• Covers the magnetism in carbon and born nitride nanostructures, bulk nanostructured magnetic materials, nanostructured magnetic semiconductors, and the fabrication of magnetic nanostructures
• Discusses emerging applications of nanomaterials such as targeted delivery of drugs, enhancement of images in MRI, ferrofluids, and magnetic computer data storage
• Includes end-of-chapter exercises and five appendices

 Physics of Magnetic Nanostructures is written for senior undergraduate and graduate students in physics and nanotechnology, material scientists, chemists, and physicists.

Preface ix

Acknowledgment xi

1 Properties of Nanostructures 1

1.1 Cohesive Energy 1

1.2 Electronic Properties 7

1.3 Quantum Dots 10

1.4 Vibrational Properties 12

1.5 Summary 17

References 17

2 The Physics of Magnetism 19

2.1 Kinds of Magnetism 19

2.2 Paramagnetism 20

2.2.1 Theory of Paramagnetism 20

2.2.2 Methods of Measuring Susceptibility 22

2.3 Ferromagnetism 25

2.3.1 Theory of Ferromagnetism 25

2.3.2 Magnetic Resonance 29

2.4 Antiferromagnetism 32

References 34

3 Properties of Magnetic Nanoparticles 35

3.1 Superparamagnetism 35

3.2 Effect of Particle Size on Magnetization 35

3.3 Dynamical Behavior of Magnetic Nanoparticles 37

3.4 Magnetic Field�]Aligned Particles in Frozen Fluids 41

3.5 Magnetism Induced by Nanosizing 47

3.6 Antiferromagnetic Nanoparticles 48

3.7 Magnetoresistive Materials 50

References 53

4 Bulk Nanostructured Magnetic Materials 55

4.1 Ferromagnetic Solids With Nanosized Grains 55

4.2 Low�]Dimensional Magnetic Nanostructures 57

4.2.1 Magnetic Quantum Wells 57

4.2.2 Magnetic Quantum Wires 61

4.2.3 Building One�]Dimensional Magnetic Arrays One Atom at a Time 65

4.3 Magnetoresistance in Bulk Nanostructured Materials 67

References 74

5 Magnetism in Carbon and Boron Nitride Nanostructures 75

5.1 Carbon Nanostructures 75

5.1.1 Fullerene, C60 75

5.1.2 Carbon and Boron Nitride Nanotubes 78

5.1.3 Graphene 81

5.2 Experimental Observations of Magnetism in Carbon and Boron Nitride Nanostructures 81

5.2.1 Magnetism in C60 81

5.2.2 Ferromagnetism in Carbon and Boron Nitride Nanotubes 87

5.2.3 Magnetism in Graphene 88

References 93

6 Nanostructured Magnetic Semiconductors 95

6.1 Electron–Hole Junctions 95

6.2 MOSFET 98

6.3 N anosized MOSFETs 99

6.4 Dilute Magnetic Semiconductors 100

6.5 N anostructuring in Magnetic Semiconductors 103

6.6 Dms Quantum Wells 106

6.7 DMS Quantum Dots 106

6.8 Storage Devices Based on Magnetic Semiconductors 107

6.9 Theoretical Predictions of Nanostructured Magnetic Semiconductors 108

References 111

7 Applications of Magnetic Nanostructures 113

7.1 Ferrofluids 113

7.2 Magnetic Storage (Hard Drives) 118

7.3 Electric Field Control of Magnetism 121

7.4 Magnetic Photonic Crystals 123

7.5 Magnetic Nanoparticles as Catalysts 125

7.6 Magnetic Nanoparticle Labeling of Hazardous Materials 127

References 129

8 Medical Applications of Magnetic Nanostructures 131

8.1 Targeted Drug Delivery 131

8.2 Magnetic Hyperthermia 132

8.3 Magnetic Separation 134

8.4 Magnetic Nanoparticles For Enhanced Contrast in Magnetic Resonance Imaging 135

8.5 Detection of Bacteria 139

8.6 Analysis of Stored Blood 144

References 146

9 Fabrication of Magnetic Nanostructures 147

9.1 Magnetic Nanoparticles 147

9.2 Magnetic Quantum Wells 149

9.3 Magnetic Nanowires 152

9.4 Magnetic Quantum Dots 153

References 154

APPENDIX A A Table of Number of Atoms Versus Size in Face Centered Cubic Nanoparticles 155

APPENDIX B Definition of a Magnetic Field 157

APPENDIX C Density Functional Theory 159

APPENDIX D Tight Binding Model of Electronic Structure of Metals 163

APPENDIX E Periodic Boundary Conditions 165

Index 167

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