What are Ferromagnetic Materials?

What are Ferromagnetic Materials?

When a magnetic field is applied to a material, ferromagnetic substances display high magnetism in the same direction as the field. First, it is necessary to define a domain.

Due to a quantum mechanical process, it is a microscopic region in ferromagnetic materials with a particular overall spin orientation.

This impact is in fact an exchange interaction. In other words, when we examine unpaired electrons, they interact with one another between two atoms & align themselves in a limited area along the magnetic field’s direction.

This mechanism of the ferromagnetic substance is referred to as ferromagnetism. By the application of a magnetic field, some materials (cobalt, gadolinium, iron, etc.) become permanent magnets.

1). Cobalt

Georg Brandt found cobalt in 1739. He was born in Riddarhyttan on June 26, 1964, & died in Stockholm on April 29, 1768. It is a ferromagnetic substance found in the earth’s crust. On the periodic table, it is represented by the symbol CO, & its atomic number is 27.

2). Iron

Iron is the only chemical element found in the earth’s crust, and it is often symbolized by the symbol Fe. Iron has the periodic table atomic number 26 and the color silvery grey. Henry W Seeley created the first electric iron in 1882, which was used to iron garments. Henry W Seeley was born on May 20, 1861 in New York & died on May 20, 1943.

3). Nickel

The chemical element nickel, which is symbolized by the symbol Ni, is also found in the earth’s crust. Nickel has an atomic number of 28 in the periodic table & the color silvery white. Axel Fredrik Crostedt created this metal; he was born in Sweden on December 23, 1722, and died on May 20, 1943.

4). Neodymium Magnet

It is a sort of powerful and permanent magnet that is seldom found in the earth’s crust, and its hue is silvery white. It is also known as an NIB, Neo, or NdFeB magnet, and its formula is Nd₂Fe₁₄B. Carl Auer Von Welsbach created this metal; he was born in Austria on September 1, 1858 and died on August 4, 1929.

5). Chromium dioxide

Chromium dioxide with the chemical formula CrO2, is insoluble in water, and is also known as Chromium (iv) oxide. Carolyn and magtrieve are two additional names for Chromium dioxide. Louis Nicolas Vauquelin discovered the metal chromium. He was born in Austria on May 16, 1763 and died in France on November 14, 1829.

6). Gadolinium

Gadolinium is a chemical element that is represented by the symbol Gd. Gadolinium has the periodic table atomic number 64. Paul-Emile Lecoq de Boisbaudran (18th April 1838 – 28th May 1912) in France & Jean Charles Galissard de Marignac (24th April 1817 – 15th April 1894) in Switzerland developed the metal gadolinium.

7). Terbium

Terbium is a kind of chemical element that is denoted by the symbol Td. Carl Gustaf Mosander created it in 1843, and it is only sometimes discovered in the earth’s crust. Carl Gustaf Mosander developed this chemical element in 1843. He was born on September 10, 1797 in Kalmar and died on October 15, 1858 in Stockholm County.

8). Dysprosium 

Dysprosium is a kind of ferromagnetic substance discovered in 1886 by Paul Emile Lecoq de Boisbaudran. He was born on April 18, 1838, and died in France on May 28, 1912. Gadolinium has the periodic table atomic number 66.

Types of the Ferromagnetic Materials

There are two kinds of ferromagnetic materials:

1). Un-magnetized ferromagnetic material and

2). Magnetized ferromagnetic material.

1). Un-magnetized ferromagnetic material

Within of each and every ferromagnetic material that has un-magnetised, the atoms arrange themselves into domains. The magnetic moment is aligned in a variety of different orientations throughout the various domains. As a result, the materials remain un-magnetized.

2). Magnetized ferromagnetic material

When an external magnetic field is supplied to the domains of un-magnetized ferromagnetic material, the domains spin and align in the direction of the magnetic field, since the domain character of the ferromagnetic material causes substantial magnetization even when a tiny magnetic field is applied.The magnetic field is much greater than the magnetic field that is present in such material. In ferromagnetism, the magnetic moments of domains align in the same direction as the magnetic field, which is why the magnetic moments of domains in ferromagnetism are parallel to the magnetic field.

Properties of the Ferromagnetic Materials

• The magnetic field significantly attracts ferromagnetic material.
• Even in the absence of a magnetic field, some substances exhibit persistent magnetism.
• When ferromagnetic materials are heated to high temperatures, they become paramagnetic.

Advantages of the Ferromagnetic Materials

• The level of resistance is high.
• The cost of hysteresis loss is modest.
• The electrical resistivity is great, while the coercivity is low.
• Permeability is quite high.
• It can withstand temperatures of up to 3000 C.
• Ferromagnetic materials provide high stability.

Disadvantages of the Ferromagnetic Materials

• Generates a very weak magnetic field.

Applications of the Ferromagnetic Materials

The ferromagnetic materials be used in the following applications:

• Transformers,
• Electromagnets
• Magnetic tape recording
• Hard drives
• Generators
• Telephones,
• Loudspeakers
• Electric motors
• Hard disk
• Magnetic Storage

There is a wide variety of materials that exhibit ferromagnetic properties; the table that follows provides examples of some of these materials.

Serial Number	Ferromagnetic materials	Curie Temperature	Boiling Point (in Kelvin-K)	Melting Point (in Kelvin-K)	Atomic Number	Density (g/cm3)
1	Cobalt	1388	3200	1768	27	8.91
2	Nickel	1043	3134	1811	26	7.87
3	Iron	627	3003	1728	28	8.901
4	Neodymium Magnet	593	3347	1297	60	7.61
5	Chromium dioxide	386	4273	648	24	4.89
6	Gadolinium	292	3273	1585	64	7.901
7	Terbium	219	3396	1629	65	8.23
8	Dysprosium	88	2840	1680	66	8.54

What is the function of curie temperature in ferromagnetic materials?

At a certain temperature, known as the Curie temperature for the material, the long-range order of a particular ferromagnetic substance suddenly disappears. Iron has a Curie temperature of around 1043 degrees Kelvin. The Curie temperature provides a rough estimate of the amount of energy that must be expended in order to destabilise the material’s long-range ordering. The thermal energy is around 0.135 eV when it is 1043 K, but it is approximately 0.04 eV when it is ambient temperature.

Magnetic hysteresis in Ferromagnetic materials

Magnetic hysteresis is most often seen in ferromagnetic materials.

When put in an external magnetic field for the purpose of magnetization, B exhibits a non-linear growth relationship with H. If H is reset to zero, the value continues to fall along the route ab.

This curve is referred to as the hysteresis curve since it follows B with H after it has already passed. (The term hysteresis refers to the delay that occurs between B & H.)

Causes of Magnetic hysteresis in Ferromagnetic materials

Residual magnetism is produced when an external magnetising field is removed (H = 0), since the magnetic moment of certain domains continues to be aligned in the direction in which the previous magnetising field was applied. This results in residual magnetism.

Residual magnetism = Br

Residual magnetism ☰ retentivity

Residual magnetism ☰ remanence

Once a magnetic field is removed from the ferromagnetic specimen, the amount of magnetic field that is still present in the sample is referred to as its retentivity.

Coercivity in Ferromagnetic materials

The amount of magnetising field that must be applied to a ferromagnetic material in order to eliminate any residual magnetism is referred to as its coercivity.