Magnetic behaviour of materials

When a material is exposed to a magnetic field it can respond in various ways.
We distinguish between:

• Diamagnetism
• Ferromagnetism
• Anti ferromagnetisme
• Ferrimagnetism
• Paramagnetism
  • Pauli paramagnetism
  • Super paramagnetism
• Spin glass magnetism

In colloquial language when we say a material is magnetic we usually mean it exhibits ferromagnetic (or sometimes ferrimagnetic) behaviour. The forces that occur in diamagnetic and paramagnetic behaviour are much weaker, and materials exhibiting such behaviour do not spontaneously produce their own magnetic field. They can more or less be considered to be non-magnetic. Diamagnetic materials have the tendency to repel lines of flux from their core, while ferromagnetic, ferrimagnetic and paramagnetic materials more or less concentrate them.

Practical example of diamagnetism: water is weakly diamagnetic, about forty times less than for example diamagnetic pyrolytic carbon, but this is enough for light objects containing a large amount of water to float if it they are in a strong magnetic field.

This frog was floating for example, using a 16 tesla electromagnet at the High Magnetic Field Laboratory at Radboud University Nijmegen in the Netherlands.

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