Ferromagnetic materials

Ferromagnetic materials are substances that exhibit strong magnetism when exposed to a magnetic field. These materials consist of atoms with a non-zero magnetic moment.

Every ferromagnetic material has its own characteristic temperature, known as the Curie temperature or Curie point, above which it loses its ferromagnetic properties.

Ferromagnetic materials can be divided into magnetically “soft” materials, such as annealed iron, which can be magnetised but do not tend to remain permanently magnetised, and magnetically “hard” materials, which do.

Permanent magnets are made from “hard” ferromagnetic materials such as AlNiCo and ferrite.

Samarium cylinder magnet dia. 3×2

Compact, powerful magnet suitable for technical applications, experiments and demonstrations of magnetic properties.

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Samarium prism magnet 10×8×5

Powerful compact magnet suitable for more demanding applications and strong magnetic fields.

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Ferrite cylinder magnet dia. 20×10

Practical ferrite magnet suitable for creative projects, technical applications and demonstrations of ferromagnetism.

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Ferromagnetic materials include:

• iron,
• cobalt,
• nickel,
• metal alloys,
• rare-earth magnets,
• magnetite and others.

What is ferromagnetism?

Ferromagnetism is the fundamental principle behind the formation of permanent magnetism in a material. Ferromagnetic materials can be magnetised by an external magnetic field and remain magnetised even after the field is removed.

Even in the absence of an external magnetic field, magnetic moments within the material can spontaneously align parallel to one another.

Only a limited number of substances are ferromagnetic. Common examples include iron, cobalt, nickel, most of their alloys and certain compounds containing rare-earth metals.

Ferromagnetism is extremely important in industry and modern technology.

Are these materials magnetic?

Is aluminium magnetic? Under normal conditions, aluminium is not ferromagnetic. It is a paramagnetic material and is only weakly attracted by a magnetic field.

Is lead magnetic? Lead is not ferromagnetic; it is diamagnetic, which means it is weakly repelled by an external magnetic field.

Is gold magnetic? Pure gold is generally non-magnetic in everyday terms and is classified as a diamagnetic material.

Is silver magnetic? Silver exhibits only very weak magnetic behaviour and, in its pure form, is diamagnetic.

Is copper magnetic? Copper in its ordinary state does not exhibit ferromagnetic behaviour and is diamagnetic.

Is chromium magnetic? Chromium has specific magnetic properties and can exhibit antiferromagnetic ordering at lower temperatures.

Is iron magnetic? Yes. Below its Curie temperature, iron is strongly attracted to magnets and is a ferromagnetic material.

Is nickel magnetic? Yes. Nickel is a ferromagnetic metal and is strongly attracted to magnets.

Is steel magnetic? Steel is usually magnetic because it contains iron.

What is paramagnetism?

Paramagnetism is a property of certain materials that are weakly attracted by a magnetic field.

When exposed to an external magnetic field, these materials develop an internal magnetic moment in the same direction as the applied field. Once the external field is removed, the induced magnetism disappears.

Paramagnetic substances include, for example, aluminium, oxygen, titanium, iron oxide, ferrofluids and AuFe alloys.

What is diamagnetism?

When a material is described as diamagnetic, it means that it exhibits only very weak magnetic activity.

Before an external magnetic field is applied, these substances have no net magnetic moment. When exposed to a magnetic field, they develop magnetisation in the opposite direction and are therefore weakly repelled.

Diamagnetic substances include copper, zinc, bismuth, silver, gold, antimony, marble, water, glass and NaCl.

Do you know which magnet is the strongest?

This type of magnet is known as a neodymium magnet and is the strongest known type of permanent magnet.

They are also known as neo magnets. They are extremely powerful while remaining relatively lightweight, making them suitable for a wide range of applications.

Many technological advances of recent decades would not have been possible without this type of magnet.

How strong are neodymium magnets?

Strong magnets can be extremely powerful. Even a small neodymium magnet can lift a load many times heavier than the magnet itself.

Be careful: small neodymium magnets can cause injury because they attract each other with considerable force.

What are neodymium magnets made from? Primarily an alloy of neodymium, iron and boron. The exact composition can vary depending on the required magnetic strength and intended application.

There are two main types:

• Sintered – manufactured from powdered alloy by pressing and subsequent magnetisation.
• Bonded – combine neodymium alloy powder with a polymer binder and allow more complex shapes to be produced.

What are neodymium magnets used for?

• hard disk drives,
• microphones, headphones and loudspeakers,
• dental prostheses,
• door catches,
• magnetic jewellery,
• anti-lock braking system sensors.