TABLE OF CONTENTS The discovery of magnetic materials was made by ancient Chinese. Two pieces of the strange substances were found to attractive or repe each other. The first practical application of magnetic materials was compasses. The term magnetic materials refers to ferromagnetic materials which exhibit high induction under magnetic field. Other materials such as paramagnetic materials and diamagnetic materials have very little magnetic induction under magnetic field and are considered non-magnetic materials.
Today, magnetic materials are indispensable materials supporting our civilization. Almost every electric appliance in a home uses some form of magnetic materials. The major applications of magnetic materials are permanent magnets, soft magnetic materials, magnetic sensors, magnetic recording materials. Unlike traditional metals such as steels, on which research efforts have declined in recent years, research efforts on magnetic materials, especially nanostructured magnetic materials have been intensified in the last two decades. This is because materials researchers have made significant progress in theory, processing and characterization methods which now make it possible to design the nanostructure and magnetic arrays with nanometer dimensions.
The bulk properties of a magnetic material are attributed to the properties of individual particles/grains and how these individual particles interact within the material. There are three cases in which the properties of each particle/ grain and their interaction determine the practical application. (1) For future quantum recording media, the magnetic dots, each of which is a recording unit, must be separated far enough so that...
