Magnetic Phenomena and Magnetic Materials

The following sections are included:

• Introduction and Brief History

• Magnetic Properties and Units

  • Magnetic Flux and Permeability

  • Basic Units

  • Magnetisation and Relative Permeability

  • Magnetic Susceptibility

• The Origin of Magnetism, Bohr Magneton

• Types of Magnetism

  • Diamagnetism

  • Paramagnetism

  • Ferromagnetism

  • Electron Structure and Magnetic Behaviour

  • Antiferromagnetism

  • Ferrimagnetism

• Effect of Temperature on Ferromagnetism —Curie Point

• Ferromagnetic Anisotropy and Magnetostriction

  • Ferromagnetic Anisotropy

  • Magnetostriction

• Ferromagnetic Domains and Domain Movement

  • Ferromagnetic Domains

  • Domain Movement During Magnetisation

• Magnetic Energy and Domain Structure — Types of Energy that Determine the Structure of Domains

  • Magnetic Exchange Energy

  • Magnetostatic Energy

  • Magnetocrystalline An isotropy Energy

  • Domain Wall Energy

  • Magnetostriction Energy

• Magnetisation and Demagnetisation of Ferromagnetic Materials, Hysteresis Loop

• Energy Losses in Magnetic Materials

  • Hysteresis Losses

  • Material Factors

  • Eddy Current Energy Losses

• Soft Magnetic Materials

  • Iron-Silicon Alloys

  • The Effect of the Addition of 3-6% Si to Fe

  • Ni-Fe Alloys (Permalloy)

  • Amorphous Alloys (Metallic Glasses)

• Hard Magnetic Materials

  • Maximum Energy Product, (BH)_max

  • Alnico Alloys

  • Rare Earth Alloys

• Ferrites — Ceramic Magnetic Materials

  • Soft Ferrites

  • Hard Ferrites

  • A Summary on “Hard” and “Soft” Materials

• Case Study — Materials in Magnetic Recording

  • Magnetic Recording Principle

  • Recording Heads

  • Recording Medium

  • Tape and Disc Processing

  • Storage Density

• Summary

• Important Concepts