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5.3. Mesoscopic and Nanostructured Materials

5.3.1 Introduction and Survey...................... 5.3.1.1 Historical Review..................... 5.3.1.2 Definitions ............................. 5.3.1.3 Specific Properties ................... 5.3.1.4 Organization of this Chapter .....

1031 1031 1032 1034 1034

5.3.2 Electronic Structure and Spectroscopy... 5.3.2.1 Electronic Quantum Size Effects . 5.3.2.2 Breakdown of the Momentum Conservation Rule ................... 5.3.2.3 Excitons in Quantum-Confined Systems.. 5.3.2.4 Vibrational Modes and Electron–Phonon Coupling. 5.3.2.5 Electron Transport Phenomena .

1035 1035 1036 1036 1040 1042

5.3.3 Electromagnetic Confinement .............. 1044 5.3.3.1 Nanoparticle-Doped Materials .. 1044 5.3.3.2 Periodic Electromagnetic Lattices........... 1048 5.3.4 Magnetic Nanostructures..................... 1048 5.3.4.1 Spin Electronics....................... 1049 5.3.4.2 Ultrahigh-Density Storage Media in Hard Disk Drives......... 1060 5.3.5 Preparation Techniques ...................... 5.3.5.1 Molecular-Beam Epitaxy .......... 5.3.5.2 Metal-Organic Chemical Vapor Deposition (MOCVD) ................. 5.3.5.3 Lithography ............................ 5.3.5.4 Nanocrystals in Matrices........... 5.3.5.5 Ex Situ Synthesis of Clusters ......

1063 1063 1064 1064 1064 1065

References .................................................. 1066

5.3.1 Introduction and Survey 5.3.1.1 Historical Review Except in the life sciences, there are only a few examples of materials that are naturally structured on scales of the order of a few to a few hundred nanometers. One

can cite, however, the natural zeolites, which constitute a group of hydrated crystalline aluminosilicates containing regularly shaped pores with sizes from 1 nm to several nanometers. This provides them the ability to reversibly adsorb and desorb specific molecules.

Part 5 3

This chapter addresses the properties of nanostructured materials considered as statistical ensembles of nanostructures. Emphasis is put on size and confinement effects, although enhancements in surface and interface properties are mentioned. After a survey and a summary of basic definitions and concepts in the introductory Sect. 5.3.1, the properties associated with electronic confinement are addressed in Sect. 5.3.2. Electronic confinement affects the spectral properties, i. e. light absorption and luminescence, mainly through quantum size effects, and the electrical conduction properties through the Coulomb blockade. Both two-dimensional systems (quantum wells) and zero-dimensional systems (quantum dots) are reviewed. Particular attention is drawn to semiconductor-doped matrices. The effects associated with confinement of electromagnetic fields are treated in Sect. 5.3.3. Numerical relationships and data for plasmon excitations of various metal nanoparticles can be found in this section. Magnetic nanostructures are addressed in Sect. 5.3.4. The two main applications of nanostructured magnetic materials, namely spin electronics, or spintronics, and ultr