Magnetic substances

The fascinating world of magnetic fields permeates all materials in our environment. While every material reacts to magnetic forces, the intensity of this interaction manifests itself in astonishingly different forms - from strong attraction to slight repulsion.

Which substances are attracted to magnets?

Ferromagnetic materials

Ferromagnetic objects adhere to magnets themselves and are also referred to as magnetizable materials because they become magnets themselves when they encounter a magnet and are considered classic magnetic materials.

A distinction is also made between magnetically soft and magnetically hard materials:

Characteristic	Magnetically soft materials	Magnetically hard materials
Magnetization	Easy to magnetize	Harder to magnetize
Demagnetization	Lose characteristics quickly	Minimal demagnetization
Remanence	Low residual magnetization	High, long-lasting residual magnetization
Application	Temporary magnetization	Are used as permanent magnets

Which materials are magnetic depends on their permeability. Here is an overview of the strongly magnetic materials:

Temperature range	Metals	Magnetic properties
At 20°C	Iron, Nickel, Cobalt	Particularly high permeability
At low temperatures	Erbium, Gadolinium, Holmium, Terbium, Dysprosium	Strong magnetic influence

There are also some special alloys that are sometimes used for magnetic shielding in high-quality technology because they have a high permeability. These include nickel-iron alloys such as mu-metal and neodymium-iron-boron compounds, which are used in the strongest permanent magnets.

Paramagnetic materials

Paramagnetic materials are easily attracted to permanent or electromagnets, but cannot be magnetized themselves and therefore cannot be used as magnets. Their permeability number is slightly above 1 - the magnetic field acting on them is therefore only minimally amplified. Paramagnetic materials, which are only very weakly attracted to magnets and cannot be permanently magnetized, include:

Aluminum
Platinum
Oxygen

Diamagnetic materials

Diamagnetic materials such as copper, zinc and water do not stick to magnets and are even easily repelled by them. This is because their permeability – their ability to absorb and transmit magnetic fields – is particularly low. The question of whether copper is magnetic can therefore be answered with a “no”.

Magnetic properties and their permeability summarized

Magnetic permeability determines the permeability of a material to magnetic fields:

Substance class	Permeability	Magnetic reaction
Ferromagnetic	> 1.000	Strongly attractive
Paramagnetic	> 1	Weakly attractive
Diamagnetic	< 1	Slightly repulsive

How do magnets affect magnetic materials?

Ferromagnetic materials consist of microscopically small elementary magnets that organize themselves in so-called Weiss domains. In the non-magnetized state, these domains are disordered, which means that their magnetic fields neutralize each other.

The magnetization process

Phase 1: Alignment

When an external magnet is brought closer, the elementary magnets in the domains begin to realign. The walls of the Weiss domains fold over until a uniform magnetization is created.

Phase 2: Pol formation

Two magnetic poles are created (north and south pole)
A high magnetic field strength is formed at both poles
Closed field lines run from the north to the south pole

Visualization of magnetic fields

The magnetic field lines can be made visible through a simple experiment:

Scatter iron filings on paper or cardboard
Place a magnetic body underneath
Observe the arrangement of the filings along the field lines

Amplification effect

When two magnets are aligned in the same force flow, their magnetic fields reinforce each other and form a common, stronger magnetic field.