Diamagnetism

The spin motion of electrons and their interaction with one another is what is responsible for the origin of magnetism. The best way to introduce different types of magnetic materials is by describing how materials respond to magnetism. It may come as a surprise to you, but all matter is magnetic. The only difference is that some materials are more magnetic than others. The level of interactions between the magnetic moments is what distinguishes them. In a few materials, there is no collective interaction of atomic magnetic moment while other materials exhibit strong atomic magnetic moment interaction. In this article, let us familiarise ourselves with the different types of magnetic materials and then we will learn about one of them in detail.

Table of Contents

Classification of Magnetic Materials

Magnetic properties of a substance are its response to an external magnetic force. Depending on the magnetic properties of solids, they can be classified into three types:

  • Diamagnetic
  • Paramagnetic
  • Ferromagnetic

Given below is the table is the definition of the different types of magnetic materials along with their examples:

Magnetic Material
Definition
Examples
Diamagnetic
Materials that are not attracted to magnetic fields
Mercury, water, copper, bismuth, and gold
Paramagnetic
Materials that are weakly attracted to magnetic fields
Magnesium, lithium, molybdenum
Ferromagnetic
Materials that are strongly attracted to magnetic fields
Iron, cobalt, and nickel

In the next section, let us look more closely into what diamagnetism is and the various properties of diamagnetic materials.

What is Diamagnetism?

Diamagnetic materials usually get repelled from a magnet. Technically, these solids create an induced magnetic field in a direction opposite to an externally applied magnetic force and are repelled by the applied magnetic field. This phenomenon is just the opposite behaviour exhibited by paramagnetic materials.

The orbital motion of electrons present in the atoms of diamagnetic solids produces magnetic fields as it creates tiny atomic current loops. When an external magnetic force is applied to a material, these current loops tend to align in such a way as to oppose the applied field.

In diamagnetic materials, there is no permanent net magnetic moment per atom as all the electrons are paired. Due to the influence of an external magnetic force, diamagnetic properties arise from the realignment of the electron paths. Most elements in the periodic table like copper, silver, and gold, are diamagnetic in nature. Sebald Justinus Brugmans discovered diamagnets in the year 1778. Michael Faraday further demonstrated that diamagnetism or magnetism is a property of a matter and every material or solid reacts accordingly.

Magnetic Susceptibilities of Diamagnetic Materials at 20°C

Km is the relative permeability which is nothing but a quantity that measures the ratio of the internal magnetization to the applied magnetic field.

Material χm=Km-1

(x 10-5)

Carbon (graphite) -1.6
Silver -2.6
Bismuth -16.6
Carbon (diamond) -2.1
Mercury -2.9
Lead -1.8
Water -0.91
Copper -1.0
Sodium chloride -1.4

The gases N2 and H2 are weakly diamagnetic with susceptibilities -0.0005 x 10-5 for N2 and -0.00021 x 10-5 for H2. The gases N2 and H2 are weakly diamagnetic with susceptibilities -0.0005 x 10-5 for N2 and -0.00021 x 10-5 for H2.

Stay tuned with BYJU’S to learn more about magnetism and diamagnetism with the help of interactive video lessons.

Frequently Asked Questions – FAQs

Q1

How are the magnetic materials classified?

Magnetic materials are classified into:
  • Diamagnetic
  • Paramagnetic
  • Ferromagnetic
  • Q2

    State true or false: Diamagnetic materials usually attract a magnet.

    False. Diamagnetic materials usually get repelled from a magnet.

    Q3

    Name three materials that are diamagnetic in nature.

    The three examples of diamagnetic materials are copper, gold, and silver.
    Q4

    What is a ferromagnetic material?

    Materials that are strongly attracted to magnetic fields are classified as ferromagnetic.
    Q5

    Name three paramagnetic substances.

    Three paramagnetic substances are: lithium, molybdenum, and magnesium.
    Test your knowledge on Diamagnetism

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