Magnetic Susceptibility

Magnetic Susceptibility is the degree of magnetization of a material in response to an applied magnetic field. It is a dimensional constant. Magnetic susceptibility explains whether a material is repelled away from the magnetic field or attracted toward a magnetic field.

In this article, we have covered Magnetic Susceptibility Definition, its Formula, Examples, and others in detail.

What is Magnetic Susceptibility?

Magnetic Susceptibility (χ) is the measure of magnetization of a material when it is kept under a magnetic field. Magnetic susceptibility of a material or substance depends on its composition, structure, and temperature. Magnetic Susceptibility is defined as χ.

Magnetic Susceptibility in electromagnetism is defined as,

Measure of how a material is magnetized in an applied magnetic field.

Magnetic Susceptibility Formula

Magnetic susceptibility is the ratio of magnetization (denoted as ‘M’) to the magnetizing field intensity (denoted as ‘H’).

χ = M/H

where,

• χ is Magnetic Susceptibility
• M is Magnetization
• H is Magnetic Field Intensity

Units of Magnetic Susceptibility

Magnetization and Magnetizing Field Intensity both quantities are both expressed in the same SI unit ‘A/m’. And [Tex]χ[/Tex] is ratio of Magnetization and Magnetizing Field Intensity, thus, magnetic susceptibility is a unitless quantity.

Types of Magnetic Material

Based on magnetic susceptibilities, magnetic materials are divided into

• Diamagnetic Material
• Paramagnetic Material
• Ferromagnetic Material

Diamagnetic Material

Diamagnetic materials have a negative magnetic susceptibility, which means they are weakly repelled by a magnetic moment. A negative magnetization is produced when the material is exposed to the external magnetic field. From this we can say that magnetic susceptibility is negative.

Examples of diamagnetic materials includes Nitrogen, copper, bromine, noble gases, chemical elements and crystalline solid materials such as [Tex]MgO[/Tex] and diamond.

Paramagnetic Material

In paramagnetic materials or substances in the absence of a magnetic field, the magnetic moments do not interact with each other, and they are randomly arranged. The atomic magnetic moments are aligned in the direction of the field whenever a field is applied and that will induce a net positive magnetization and positive susceptibility.

Magnetic lines of forces produced by the applied field are attracted towards the paramagnetic substance. The magnetic susceptibility of paramagnetic materials is positive. Examples of paramagnetic material include oxygen, Li, Na, Mn and all the platinum group metals.

Ferromagnetic Material

In the absence of an external magnetic field, ferromagnetic materials contain magnetic dipole moments that are parallel to each other. Magnetic susceptibility is large and positive for ferromagnetic material. The source of ferromagnetic is the spin of the electrons.

Examples of ferromagnetic substances or materials include nickel, cobalt and iron

Factors Influencing Magnetic Susceptibility

Magnetic susceptibility is affected by material characteristics and temperature.

Temperature Effects

Magnetic susceptibility changes with temperature. The relationship between the magnetic susceptibility and temperature depends upon the type of the magnetic substances which is considered such as diamagnetic, paramagnetic or ferromagnetic materials.

For diamagnetic material magnetic susceptibility is independent of temperature. Their negative susceptibility arises due to motion of electrons which cannot be affected by temperature.

For paramagnetic materials magnetic susceptibility varies inversely with the temperature.

For ferromagnetic material magnetic susceptibility decreases with the rise in temperature according to Curie’s Law.

Material Composition

Composition and structure of a material greatly influence its magnetic susceptibility. Materials with unpaired electrons, such as transition metals, tend to exhibit paramagnetic behaviour, while those with no unpaired electrons, such as noble gases, exhibit diamagnetic behaviour.

Based on the corresponding magnetic properties, Magnetic susceptibility varies between substances. Due to their ability to resist magnetic field, Diamagnetic materials have negative susceptibility. Paramagnetic materials have a positive susceptibility because they are weakly attracted to magnetic fields. Ferromagnetic materials have a very high positive susceptibility because of their strong attraction to magnetic fields.

Magnetic Susceptibility Units

We know that magnetic susceptibility χ, is defined as,

χ = M/H

Thus, magnetic susceptibility ‘χ’ is dimensionless quantity.

Techniques for Measuring Magnetic Susceptibility

There are several different methods for measuring magnetic susceptibility such as

• Faraday’s Scale
• Guoy’s Scale
• Inductive Method with SQUID magnetometer
• Inductive Method with magnetic balance,
• Inductive Method with vibrating sample magnetometer (VSM)

Each method has its advantages and is suitable for different types of materials. Susceptibility can be determined by measuring magnetisation of a material, but very high sensitivity is required for weakly magnetic materials, which can be challenging for small samples.

Magnetic Susceptibility (of Magnetic Materials at 20°C)

At 20°C, magnetic susceptibility of some materials is added in the table,

Elements	Magnetic Susceptibility
Ammonia	-0.26
Bismuth	-16.6
Mercury	-2.9
Silver	-2.6
Carbon (Diamond)	-2.1

Challenges in Measuring Magnetic Susceptibility

Magnetic Susceptibility of any material is not easily measured. There are various challenges that comes while measuring Magnetic Susceptibility that are,

Temperature Sensitivity and Accuracy

Measuring magnetic susceptibility accurately at different temperatures can be challenging due to temperature fluctuations and the temperature dependence of susceptibility

Sample Size and Shape Effect

Size and shape of material sample can influence the measurement of magnetic susceptibility, especially in techniques that assume uniform magnetization. Correcting for these effects is crucial for accurate results.

Read More,

• Magnetism
• Ferromagnetism
• Diamagnetism

Conclusion

Understanding magnetic susceptibility is essential for studying magnetic properties of materials and their applications in a number of fields. Magnetic susceptibility indicates behavior of a material elaborating whether a material can get attracted or repelled out within a magnetic field.

Frequently Asked Questions on Magnetic Susceptibility

What is Magnetic Susceptibility?

Magnetic susceptibility is the measure of how much a material is magnetised in an applied magnetic field.

What does Magnetic Susceptibility Depend On?

Magnetic susceptibility of a magnetic substance or material is depends on the temperature and the strength of the magnetising field.

What is Significance of Magnetic Susceptibility?

Magnetic susceptibility provides valuable information about the magnetic properties of materials, which is essential for designing magnetic materials for differentiffernet applications, including electronics, data storage, and medical imaging.

Which Material has Negative Magnetic Susceptibility?

For diamagnetic material magnetic susceptibility is negative. It is positive for paramagnetic material and ferromagnetic material has large positive magnetic susceptibility.

What are Differences between Diamagnetic, Paramagnetic, and Ferromagnetic Materials?

• Diamagnetic materials have negative susceptibility and are weakly repelled by magnetic fields.
• Paramagnetic materials have positive susceptibility and are weakly attracted by magnetic fields.
• Ferromagnetic materials have strong positive susceptibility and exhibit spontaneous magnetization.

What is Formula for Magnetic Susceptibility?

Magnetic susceptibility which is denoted by (χ), is the ratio of magnetization ‘M’ within material to magnetizing field intensity (denoted as ‘H’) and it is expressed as,

χ = M/H