Ferromagnetic Materials (Definition, Causes, Properties)

The term “ferromagnetism” comes from the term “ferrous,” which alludes to iron, the first metal to be discovered with magnetic field-attractive properties. When a magnetic field is applied to ferromagnetic materials, it causes them to exhibit high magnetism in the same direction as the field.

Ferromagnetism is a magnetic property that certain materials, such as iron, cobalt, alloys, and others, have. It’s a phenomenon in which certain materials develop persistent magnetic or attracting properties. Ferromagnetism (together with the related phenomena of ferrimagnetism) is the most powerful type of magnetism and is responsible for the common phenomenon of magnetism in daily magnets.

It’s a small area in ferromagnetic materials that has a certain overall spin orientation due to quantum mechanical effects. This is a genuine trading interaction. Ferromagnetism is a feature that takes into account not only a material’s chemical make-up but also its microstructure and crystalline structure.

A refrigerator magnet, which is used to keep notes on a refrigerator door, is an everyday example of ferromagnetism. “The quality of magnetism originally obvious to the ancient world, and to us today” is the attraction between a magnet and ferromagnetic material. In an unmagnetized ferromagnetic material, atomic dipoles in tiny areas called domains are all orientated in the same direction.

The domains have a net magnetic moment even when there is no external magnetizing force. On the other hand, the magnetic moments of neighboring domains are in opposite directions. They cancel each other out, resulting in a net magnetic moment of zero for the substance.

Example of ferromagnetism

All of these domains align in the direction of the applied magnetic field when an external magnetic field is applied. As a result of this process, the material becomes strongly magnetised in a direction parallel to the magnetising field. Magnetically “soft” materials like annealed iron, which can be magnetized but do not tend to stay magnetized, and magnetically “hard” materials, which do, are the two types of ferromagnetic materials.

The magnetic moments of neighboring domains, on the other hand, are in opposing directions. They cancel each other out, resulting in the material’s net magnetic moment being zero. When an external magnetic field is applied, all of these domains align in the direction of the applied field.

The material is strongly magnetized in a direction parallel to the magnetizing field as a result of this process. Permanent magnets are created from “hard” ferromagnetic materials like alnico and ferrimagnetic materials like ferrite that undergo special processing in a strong magnetic field during manufacture to align their internal microcrystalline structure, making them extremely difficult to demagnetize.

Ferromagnetic materials are a class of materials that, when exposed to a magnetic field, tend to exhibit or display high magnetism in the direction of the field. The alignment patterns of these materials’ component atoms are primarily responsible for their magnetic. These atoms have a tendency to behave like basic electromagnets.

Historically, the term ferromagnetism was applied to any substance capable of spontaneous magnetization: the formation of a net magnetic moment in the absence of an external magnetic field; in other words, any material capable of becoming a magnet.

Metals make up the majority of ferromagnetic materials. Iron, Cobalt, Nickel, and other ferromagnetic materials are common examples. In addition, ferromagnetic materials include metallic alloys and rare earth magnets.

The oxidation of iron into an oxide produces magnetite, a ferromagnetic substance. It has a 580°C Curie temperature. It was once thought to be a magnetic material. Magnetite is the most magnetic of all-natural minerals on the planet.

Properties of Ferromagnetic Materials:

  • In domains, the atoms of ferromagnetic substances have a persistent dipole moment.
  • Atomic dipoles in ferromagnetic materials are aligned in the same direction as the external magnetic field.
  • The magnetic dipole moment is big and oriented in the magnetising field’s direction.
  • The magnetization intensity (M) is exceedingly high and positive, and it changes in a linear relationship with the magnetizing field (H). As a result, the material’s composition determines saturation.
  • Magnetic susceptibility is quite high and positive. Magnetic susceptibility is defined as Xm = M ⁄ H, where M is the magnetization intensity and H is the applied magnetic field strength.
  • The magnetic flux density of the material will be exceedingly high and positive. Magnetic field lines become extraordinarily thick inside ferromagnetic materials. B = ε0 (H + M) magnetic flux density, where ε0 is the magnetization intensity, H is the applied magnetic field strength, and M is the magnetic permittivity of free space.
  • The relative permeability is also extremely high, and it changes in a linear relationship with the magnetic field. The magnetic field inside the material is much stronger than the magnetic field outside of it. They have a proclivity for drawing in a lot of force lines from the material.
  • The field aggressively attracts ferromagnetic materials. They tend to adhere to the poles where the field is stronger in a nonuniform field.
  • Because the field is strongest at poles, if ferromagnetic powder is placed in a watch glass placed on two poles pieces that are sufficiently apart, powder accumulates on the sides and exhibits depression in the middle.
  • Because of the higher temperature, a ferromagnetic material loses its ferromagnetic properties when liquefied.

Hysteresis is a feature of ferromagnetic materials that allows them to retain their magnetization when an external field is removed. When a ferromagnetic substance is exposed to an external magnetic field, it does not completely demagnetize. To return the material to zero magnetization, a magnetic field in the opposite direction must be applied.

When the magnetization of the material is measured in terms of magnetic flux density (B) and the external magnetic field intensity (H), a loop is formed. The hysteresis loop is what it’s called. Ferromagnetic materials are used in a variety of industries.

Electric motors, telephones, generators, loudspeakers, transformers, and the magnetic stripe on the back of credit cards all use them. Temperature affects ferromagnetic properties. Ferromagnetic substances become paramagnetic when heated to a high enough temperature.