Macroscopic objects made of magnetic materials have been known to mankind for several thousand years and are widely used in various fields of human activity. With the development and practical implementation of microelectronics, and more recently nanoelectronics, it has become possible to develop and manufacture magnetic nanomaterials, dramatically expanding the scope of magnetics in modern technologies. Today, magnetic nanomaterials and nanostructures are key components of advanced information technologies. They are widely used in eMobility, medicine, sensors, robotics, etc., and have significant potential for application in prospective smart wearables and human-machine interfaces. This volume outlines recent research in the field of functional magnetic and spintronic materials. Each of the 10 chapters in the volume is self-contained, allowing the topics to be explored independently of the material in other chapters. The book covers the entire “life cycle� of magnetic/spintronic nanomaterials: from theoretical and numerical studies of their properties (Ch. 1), fabrication and experimental study of film systems (Ch. 2), fabrication of nanostructures (Ch. 3), study of electromagnetic phenomena occurring in such nanostructures (Chs. 4-10), to the use of these nanostructures in new technologies, particularly in spintronic energy harvesting (Ch. 9) and quantum sensing (Ch. 10). Some of the contributions to this volume were presented as lectures and reports at the Advanced Research Workshop “Functional Spintronic Nanomaterials for Radiation Detection and Energy Harvesting� (25–27 September 2023, Kyiv, Ukraine), which was supported by the NATO Science for Peace and Security Programme.