In our society driven by our electronic devices, the invisible force of magnetic fields constantly interacts with our technology, often in ways we would prefer to avoid. Our technological environment is shaped by these magnetic fields, whether we notice them or not. They range from the delicate pull of diamagnetism to the tug of ferrimagnetism. But how do we keep our devices safe from unwanted magnetic interference?
5 Types of Magnetic Fields
Magnetism is a fundamental force of nature. It’s a force that most of us take for granted, but it can and does impact the functionality and longevity of our electronic devices.
By understanding the different types of magnetic fields—each with its unique characteristics and effects—we can better protect and enhance the performance of these devices. In this article, we explore five key types of magnetism.
1. Diamagnetism
When materials are exposed to an external magnetic field, they produce diamagnetism. This is a weak, temporary magnetism. It happens when the electrons’ movement creates tiny internal magnetic fields. When a magnetic field interacts with diamagnetic materials, they create opposing magnetic fields.
The opposing magnetic fields create a repelling effect. This means the diamagnetic materials pushed away from the magnetic field. Contrast this to ferromagnetic materials, which are attracted to magnetism.
It’s worth noting the field diamagnetism creates is very weak. It’s only observable when the external magnetic field is relatively strong.
Examples of Diamagnetic Materials
- Water: Water has some truly unique characteristics within magnetic fields. For example, researchers have found that water droplets levitate when exposed to superconductors.
- Gold, Silver, and Copper: These precious metals also exhibit diamagnetic properties. In theory, this means they could be used in applications where EMI is a concern, though this is uncommon.
- Organic Compounds: Most organic compounds are predominantly diamagnetic. This is why we can use magnetic resonance imaging (MRI) and other technologies in medical settings.
For equipment that must operate within a magnetic field, diamagnetism is a key consideration. You wouldn’t want the system and its housing to be pushing against each other, so it’s important to be aware of this constraint even though diamagnetism doesn’t create electromagnetic interference.
2. Paramagnetism
Imagine you have a bunch of tiny bar magnets that can freely spin around. Normally, they spin in all directions, so they don’t create any noticeable magnetism. But what if you bring a big, strong magnet close to them? The tiny bar magnets will line up with the big magnet’s field. When you take the big magnet away, though, they go back to spinning randomly. This is a bit like what happens with paramagnetism, but instead of tiny magnets, we’re talking about the electrons in certain materials.
Paramagnetism happens in materials that have electrons acting like “lone rangers.” These electrons don’t have a partner spinning the opposite way, so they have a small magnetic field around them. When you put these materials in a magnetic field, the lone ranger electrons line up with the field. This causes the material to be weakly attracted to the magnetic field, but only while the field is there. Take the field away and the material goes back to not being magnetic.
Since these fields only exist when a magnet is present, and they tend to be relatively weak, they don’t create the kind of interference we’d expect to cause problems with electronic devices.
Examples of Paramagnetic Materials
- Aluminum
- Magnesium
- Transition Metal Compounds such as iron oxide, copper sulfate, and titanium dioxide.
Paramagnetism is a temporary and weak magnetic field in the presence of an external magnet. It happens because of unpaired electrons within the material, but they do not generate significant electromagnetic interference. So, they are generally safe for use in electronic applications.
3. Ferromagnetism
Ferromagnetism is a strong and permanent magnetic response. This phenomenon occurs in materials that exhibit spontaneous magnetization. Spontaneous magnetization simply means the materials are naturally magnetic, even in the absence of an external magnetic field.
At the atomic level, a ferromagnetic material’s electrons align parallel to each other. When that happens over a large number of atoms, the field becomes larger.
Now, the temperature of the material also matters. The material’s Curie temperature is the point at which the material loses its magnetism. If you heat a magnet to this temperature or hotter, it will lose its magnetism. When it cools back down, it can become magnetic again.
Ferromagnetism is often what we think of when we think of magnetism. Including big bar magnets and smaller items being attracted to it.
Electromagnetic Interference
For those of us who think about electromagnetic interference (EMI), ferromagnetic materials play a central role.
Due to their strength, ferromagnetic magnetic fields can interfere with electronic devices. This is particularly noticeable in sensitive devices or in situations where precise electronic functioning must be maintained.
Examples of Ferromagnetic Materials
- Iron is the namesake for Ferromagnetism (Iron’s Latin name is Ferrum, which is how we get its symbol Fe)
- Nickel
- Cobalt
4. Antiferromagnetism
When the magnetic moments of neighboring particles point in opposite (antiparallel) directions, antiferromagnetism occurs. By opposite directions, we mean one particle’s north pole is pointed upward, while its neighbor’s is pointed downward, and so on.
What’s interesting about antiferromagnetic materials is each of these tiny magnetic fields cancels the other out. Because of this canceling effect, the material ends up with no net magnetization. That’s to say, the material doesn’t act as a magnet, even though it’s made up of many tiny ones.
Examples of Antiferromagnetic Materials
- Manganese Oxide
- Chromium Oxide
- Iron Oxide (FeO) (even though iron is typically associated with ferromagnetism!)
Despite the magnetic activity, antiferromagneticism does not produce a magnetic field, so it does not disrupt electronic devices.
5. Ferrimagnetism
Ferrimagnetism is a magnetic phenomenon that shares similarities with ferromagnetism but with a twist. Like antiferromagnetism, the magnetic moments within the material align in opposite directions, but some of those moments are stronger than others. This imbalance leads to a situation where a net magnetization remains across the whole material.
Ferrimagnetism arises due to the atomic structure and composition of certain materials, which allows for ions with different magnetic moments to coexist. These differing moments align in opposite directions, but they do not completely cancel each other out. The result is a material that, despite having internally opposing magnetic arrangements, displays magnetization. This characteristic of ferrimagnetic materials allows them to behave like magnets. But these are usually weaker magnets than their ferromagnetic counterparts.
Does Ferrimagnetism Produce Electromagnetic Interference?
Given that ferrimagnetic materials exhibit a net magnetization, they can produce EMI under certain conditions. However, the strength of this interference depends on the material’s net magnetization level.
So, while ferrimagnetic materials can influence nearby electronic devices, the extent of this influence is generally less pronounced.
Examples of Ferrimagnetic Materials
- Magnetite
- Ferrites: (a class of ceramic compounds composed of iron oxide)
The unique characteristics of these ferromagnetic materials make them very useful for shielding devices from electromagnetic interference. Their ability to absorb and redirect magnetic fields creates barriers that protect sensitive electronic components.
Protect Your Devices from EMI with Eagle Magnetic
The importance of efficient shielding in protecting our electronic equipment becomes evident when navigating the types of magnetic fields. Avoiding unwanted electromagnetic interference becomes not only possible but also a reality when Eagle Magnetic’s experience is by your side. Learn more about the was Eagle Magnetic supports your work through perfectly designed and engineered magnetic shielding solutions.
