Magnetic materials, commonly referred to as magnetic material refers to the ferromagnetic material, is an ancient and very versatile functional material, and the magnetic material as early as 3,000 years ago, people have been recognized and applied, for example, ancient China with a natural magnet as a compass . Modern magnetic materials have been widely used in our life, such as permanent magnet materials used as motors, used in transformers core material, used as a memory of the magneto-optical disk, floppy disk and so on computer. Big bit of information that the magnetic materials and information technology, automation, mechanical and electrical integration, national defense, all aspects of national economy are closely related. However, it is generally believed that a magnetic material refers to a substance that can generate magnetism directly or indirectly from excessive elements such as iron, cobalt, nickel and their alloys. Magnetic materials according to magnetization demagnetization can be divided into soft magnetic materials and hard magnetic materials. After magnetization easy to remove the magnetic material called soft magnetic material, not easy to demagnetize material called hard magnetic material. In general, soft magnetic remanence is small, hard magnetic remanence larger.