6 Hollow Magnetic Nanoparticles . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137
Hafsa Khurshid, Zohreh Nemati, Óscar Iglesias, Javier Alonso,
Manh-Huong Phan, and Hariharan Srikanth
6.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138
6.2 Synthesis of Hollow MNPS . . . . . . . . . . . . . . . . . . . . . . . . . . . 139
6.3 Magnetic Properties of Hollow MNPs . . . . . . . . . . . . . . . . . . . 143
6.3.1 Basic Magnetic Behavior . . . . . . . . . . . . . . . . . . . . . . 143
6.3.2 Surface Anisotropy and Spin Disorder . . . . . . . . . . . . . 144
6.3.3 Exchange Bias Versus Minor Loops . . . . . . . . . . . . . . 145
6.4 Evolution from Core–Shell to Core–Void–Shell to Hollow . . . . 147
6.5 Monte Carlo Simulations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149
6.6 Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152
6.7 Summary and Future Outlook . . . . . . . . . . . . . . . . . . . . . . . . . 155
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 156
7 Nature Driven Magnetic Nanoarchitectures . . . . . . . . . . . . . . . . . . 159
María Luisa Fdez-Gubieda, Lourdes Marcano, Alicia Muela,
Ana García-Prieto, Javier Alonso, and Iñaki Orue
7.1 An Introduction to Magnetotactic Bacteria . . . . . . . . . . . . . . . . 160
7.2 Biomineralization Process of the Magnetosome . . . . . . . . . . . . 163
7.3 Magnetic Properties of Magnetosomes and Magnetosome
Chains in Magnetospirillum gryphiswaldense . . . . . . . . . . . . . . 166
7.3.1 The Verwey Transition in the Magnetosomes . . . . . . . . 166
7.3.2 Magnetic Interactions in the Magnetosome Chain . . . . . 166
7.3.3 Magnetization Process of the Chain:
The Stoner-Wohlfarth Approach . . . . . . . . . . . . . . . . . 169
7.4 Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171
7.5 Future Perspectives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 175
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 176
8 Magnetic Self-Assembling of Spherical Co Nanoparticles Used
as Building Blocks: Syntheses, Properties and Theory . . . . . . . . . . 181
Johannes Richardi, C. Petit, and Isabelle Lisiecki
8.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 182
8.2 Synthesis of Uniform Spherical Co Nanoparticles . . . . . . . . . . . 184
8.2.1 Synthesis by Micellar Approach . . . . . . . . . . . . . . . . . 184
8.3 Synthesis by Organometallic Approach . . . . . . . . . . . . . . . . . . 190
8.4 Assemblies of Cobalt Nanoparticles . . . . . . . . . . . . . . . . . . . . . 192
8.4.1 Key Parameters Involved in the Nanoparticle
Organization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 192
8.5 2D Self-Organizations of Cobalt Nanoparticles Synthesized by
Micellar Approach . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 194
Contents
ix
Hafsa Khurshid, Zohreh Nemati, Óscar Iglesias, Javier Alonso,
Manh-Huong Phan, and Hariharan Srikanth
6.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138
6.2 Synthesis of Hollow MNPS . . . . . . . . . . . . . . . . . . . . . . . . . . . 139
6.3 Magnetic Properties of Hollow MNPs . . . . . . . . . . . . . . . . . . . 143
6.3.1 Basic Magnetic Behavior . . . . . . . . . . . . . . . . . . . . . . 143
6.3.2 Surface Anisotropy and Spin Disorder . . . . . . . . . . . . . 144
6.3.3 Exchange Bias Versus Minor Loops . . . . . . . . . . . . . . 145
6.4 Evolution from Core–Shell to Core–Void–Shell to Hollow . . . . 147
6.5 Monte Carlo Simulations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149
6.6 Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152
6.7 Summary and Future Outlook . . . . . . . . . . . . . . . . . . . . . . . . . 155
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 156
7 Nature Driven Magnetic Nanoarchitectures . . . . . . . . . . . . . . . . . . 159
María Luisa Fdez-Gubieda, Lourdes Marcano, Alicia Muela,
Ana García-Prieto, Javier Alonso, and Iñaki Orue
7.1 An Introduction to Magnetotactic Bacteria . . . . . . . . . . . . . . . . 160
7.2 Biomineralization Process of the Magnetosome . . . . . . . . . . . . 163
7.3 Magnetic Properties of Magnetosomes and Magnetosome
Chains in Magnetospirillum gryphiswaldense . . . . . . . . . . . . . . 166
7.3.1 The Verwey Transition in the Magnetosomes . . . . . . . . 166
7.3.2 Magnetic Interactions in the Magnetosome Chain . . . . . 166
7.3.3 Magnetization Process of the Chain:
The Stoner-Wohlfarth Approach . . . . . . . . . . . . . . . . . 169
7.4 Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171
7.5 Future Perspectives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 175
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 176
8 Magnetic Self-Assembling of Spherical Co Nanoparticles Used
as Building Blocks: Syntheses, Properties and Theory . . . . . . . . . . 181
Johannes Richardi, C. Petit, and Isabelle Lisiecki
8.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 182
8.2 Synthesis of Uniform Spherical Co Nanoparticles . . . . . . . . . . . 184
8.2.1 Synthesis by Micellar Approach . . . . . . . . . . . . . . . . . 184
8.3 Synthesis by Organometallic Approach . . . . . . . . . . . . . . . . . . 190
8.4 Assemblies of Cobalt Nanoparticles . . . . . . . . . . . . . . . . . . . . . 192
8.4.1 Key Parameters Involved in the Nanoparticle
Organization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 192
8.5 2D Self-Organizations of Cobalt Nanoparticles Synthesized by
Micellar Approach . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 194
Contents
ix