Chapter 3 - Magnetically Active Asymmetric Nanoheterostructures Based on Colloidal All-Inorganic Multicomponent Nanocrystals

Colloidal inorganic nanocrystals (NCs) constitute an important class of advanced nanomaterials owing to the flexibility with which their dimensionality-dependent physical–chemical properties can be controlled by engineering their compositional, structural, and geometric features in the synthesis stage and the versatility with which they can be exploited in disparate technological fields, spanning from optoelectronics, energy conversion/production to catalysis, and biomedicine. In recent years, building upon knowledge acquired on the thermodynamic and kinetic processes that underlie NC evolution in liquid media, synthetic nanochemistry research has made tremendous advances, opening new possibilities for designing, creating, and mastering increasingly complex NC-based assemblies, in which sections of different materials are grouped together into free-standing, easily processable multifunctional nanocomposite systems. This chapter will provide an overview of this fast-growing research field by illustrating progress achieved in the wet-chemical development of last-generation breeds of so-called hybrid or heterostructured nanocrystals (HNCs) in asymmetric non-core/shell geometries, in which distinct material modules are interconnected in heterodimer, heterooligomer, and anisotropic multidomain architectures via heteroepitaxial bonding interfaces of limited extension. The focus will be on HNCs that incorporate at least one magnetic material component combined with semiconductors and/or plasmonic metals, which hold potential for generating enhanced, unconventional magnetic behavior, on one side, and diversified or even new properties and capabilities, on the other side. Various synthetic strategies, all based on the manipulation of seeded-growth techniques, will be described and rationally interpreted within the framework of the currently understood mechanisms of colloidal heteroepitaxy.