Preface

Permanent magnets are powerful magnets that maintain their magnetic properties for a long time. Modern permanent magnets are important for academic research, defense applications, energy technologies, and more. There are several types of permanent magnets, each manufactured differently from different materials with different properties. The method of manufacturing and fabrication of permanent magnets is important for the design and development of new devices and their assembly into functional systems for different applications in different fields. The material used for making a permanent magnet also possesses specific properties such as the high value of coercivity and retentivity; the area of the magnet hysteresis curve should also be large. Permanent magnets can be bonded magnets or polymer-free magnets, with rare-earth materials or without them.

This book presents an update and overview of the principles and recent developments in various families of permanent magnets. The chapters discuss permanent magnets and their manufacturing processes. They also present the latest research developments in different types of modern permanent magnets, scientific advances in manufacturing techniques, and the applications of magnets, providing insight into the development of future devices.

This book contains six chapters. Chapter 1 introduces the topic of permanent magnets. Chapter 2 discusses light–matter interaction in 2D magnets. Chapter 3 explains the environmental impact of permanent magnets. Chapters 4 and 5 deal with the hysteresis model and magnetized plasma. Finally, Chapter 6 presents recent advances in nanocrystalline permanent magnets of different materials.

This book is a useful resource for students, researchers, academicians, and professionals. It presents a broad range of ideas and proposes possible solutions for the development of effective permanent magnets.

**Dipti Ranjan Sahu**

Faculty of Health, Department of Biology, Chemistry and Physics, School of Natural and Applied Sciences, Natural Resources and Applied Sciences, Namibia University of Science and Technology, Windhoek, Namibia

**1**

**Chapter 1**

Applications

ties of the permanent magnets [4–6].

**2. Basics of permanent magnets**

are mentioned as follows:

• Coercive force/coercivity

phase of the magnetic compound [8, 9].

• Magnetic domains and domain walls

• Anisotropy

*Dipti Ranjan Sahu*

**1. Introduction**

Introductory Chapter: Modern

Permanent Magnets – Basics and

Permanent magnets are highly magnetized functional hard materials, which do not lose magnetism over time due to the generation of magnetic field by the internal structure of the material itself [1–3]. These modern permanent magnets are made from a "cocktail" of minerals which can include iron, neodymium, samarium, cobalt and nickle. Normally, the functionality of the permanent magnets depends on the intrinsic properties of the base compound. It is commonly known that permanent magnets are source of magnetic field. The composition, extrinsic properties such as microstructure and processing method of materials are define the magnetic proper-

The magnetic flux with no energy input defines the uniqueness of permanent magnets. The performance of permanent magnets is estimated based on the magnetization (*M*) and maximum energy product and the magnetic parameter such as

In addition, to above indicator, some basic requirements of permanent magnets

Shape anisotropy, magneto-crystalline anisotropy and stress anisotropy contribute

High coercivity is the requirement for the development of permanent magnets, which can be achieved by controlling the microstructure of the major constituent

(*BH*)max, spontaneous magnetization and coercive forces [7].

towards the anisotropy behavior of permanent magnets [8].
