Preface Free

Human beings are experiencing a critical moment nowadays with the occurrence of different pandemics, climate change, or depletion of conventional natural sources to produce energy. Within this context, magnetic nanoparticles have evolved as an intriguing type of material offering different solutions to the ongoing challenges we are currently facing based not only on their magnetic properties but also on their optical and biomedical ones, expanding their possible usage from permanent magnets in energy production to multimodal therapy for biomedicine or magnetocatalysis. It is well known how the magnetic properties change with the particle size, but during the last decade, new magnetic (and magnetic-based) nanoparticles with anisotropic shapes, or coupled to other domains (optical, plasmonic, semiconductor, and/or electrochemical), have appeared, leading to new research work to understand their properties at the nanoscale.

This book aims to provide new developments in the synthesis, characterization, and applications of magnetic nanoparticles. Chapter 1 focuses on the functionality of surface-modified magnetite nanoparticles within magnetorheological fluids, revealing their capacity to form stable chain structures and highlighting the influence of particle sizes, shapes, surface modifications, and polymer molecular weights on rheological properties. In Chapter 2, innovative synthetic strategies are unveiled to improve the magnetic properties of exchange-coupled heterostructures to achieve room-temperature exchange bias magnets. The authors predict the introduction of defect engineering as an avenue to induce magnetic features in standard spinel ferrites. The emerging class of magnetically contrasted nanoconsolidates takes the spotlight in Chapter 3, detailing the application of Spark Plasma Sintering to produce effective E-biased solids, emphasizing the importance of operating conditions and precursor morphology on the magnetic properties of engineered solids. Chapter 4 delves into magnetic micro- and nano-disks, bridging the benefits of thin films and nanoparticles, while Chapter 5 explores the realm of magneto-optics and magneto plasmonics in nanomaterials, summarizing the key achievements and trends in these fields. Chapter 6 points to the intricate interplay between polydispersity, coercivity, and exchange bias to understand the thermal dependence of magnetic properties in ultrasmall nanoparticles. The book progresses to Chapter 7, which focuses on characterizing magnetic nanoparticles for magnetic hyperthermia, offering insights into experimental techniques. Chapter 8 studies Electron Magnetic Resonance as a technique capable of studying magnetic properties sensitive to changes in anisotropy and exchange interactions, while Chapter 9 explores the nanoscale magnetic anisotropy determination using advanced microscopy methods. Chapter 10 showcases giant magnetoimpedance effect-based detectors for the ultra-sensitive detection of magnetic nanoparticles, outlining materials, geometries, and optimization strategies. The profound synergy between magnetic fields and nanoparticles forms the essence of Chapter 11, underscoring their potential in technological and biomedical advancements. Hybrid inorganic magnetic-based nanostructures take the stage in Chapter 12, highlighting their multifunctional performance in biomedicine, energy production, and environmental remediation. Chapters 13 to 15 navigate diverse applications, from exploring antiviral activity against respiratory viruses to integrating magnetic nanoparticles into printed nano/microstructures and investigating their role in diamond quantum sensing.

In conclusion, this book addresses different levels of readers with a general background in physics and chemistry as well as medical and materials science. We do believe that this book will provide the reader with an overall overview of the state of the art and the latest prospects in this fast-evolving field.

Alberto López-Ortega and Alejandro G. Roca