Is graphite magnetic? Find out the truth

I’ve noticed there’s some debate around whether graphite is magnetic or not. As a professional neodymium magnets supplier, I decided to dig into the details and get to the bottom of this carbon conundrum.

Let me walk you through what I uncovered in my research on graphite magnetism.

Is graphite magnetic?

The short answer is that graphite is generally considered non-magnetic or diamagnetic. This means pure graphite does not act like a magnet, and in fact, it can slightly repel magnetic fields due to the arrangement of its carbon atoms.

However, there are some complexities and exceptions to this rule:

• Graphite can display weak diamagnetism due to its paired electrons and structure.
• Under certain conditions like lattice defects or proton irradiation, graphite may exhibit ferromagnetism.
• Factors like impurities and allotrope structure can influence graphite’s magnetic properties.
• Single-layer graphene displays exceptional behaviors, as does graphite in some external fields.
• Recent advances have shown ways to alter graphite to make it magnetic.

So while natural graphite tends to be non-magnetic, its properties are complex. Under specific circumstances, induced changes can lead to magnetic behaviors.

Let’s unpack the details…

Diamagnetism: Graphite’s default state

The key to understanding graphite’s magnetism lies in its carbon atom structure.

Graphite has a layered design, with each atom bonded to three neighbors in a lattice that looks like a honeycomb. The spare electron forms a “pi bond” with the layers above and below.

This pi bond delocalizes the electron, allowing it to roam freely. And that’s why graphite conducts electricity despite being considered a semimetal.

But what does this mean for magnetism?

Well, with their electrons all paired up, each carbon atom has no net magnetic moment. So the layers of atoms tend to cancel each other out rather than aligning magnetically.

That’s why graphite defaults to diamagnetism – a property where it weakly repels external magnetic fields rather than getting attracted like iron.

To visualize it, you can think of diamagnetic materials as slight magnetic mirrors. They reflect back the field hitting them because their paired electrons resist reorientation.

So that’s why pure graphite generally shows little magnetism – each atom counters the tiny field of its neighbor.

Luckily, graphite has additional quirks that introduce some magnetic personality…

When graphite gets ferromagnetic

Contrary to popular belief, pristine graphite can demonstrate ferromagnetism, even at room temperature.

The secret lies in those pi-bonded electron layers. Turns out, they can interact magnetically depending on how the sheets stack together.

Researchers found that when two graphene layers have opposing diamagnetic orientations, their magnetic moments cancel out (antiferromagnetic stacking). With other orientations, they may generate small magnetic fields (ferromagnetism).

But layer orientation alone isn’t responsible for graphite’s hidden magnetism. Structural defects also play a crucial role.

You see, no material is perfect. When graphite forms, the layers leave behind topological defects: missing atoms, 8-membered carbon rings instead of hexagonal ones, that kind of thing.

These defects act as the magnetic personality graphite lacks. They introduce free electrons just like doping graphite with other elements would. Except here, magnetism stems from carbon alone!

Lattice defects create 2D magnetic networks

To study defect magnetism, scientists use techniques like scanning tunnelling microscopy. This lets them probe the structure of graphite one layer at a time.

Thanks to microscopy advances, researchers from the Netherlands found something incredible in 2008.

It turns out many defect sites couple magnetically with their neighbors. This forms a 2D network of magnetism within each graphene sheet!

Network of magnetically coupled defects (doi.org/10.1038/nphys1399)

The Dutch team showed these 2D bands connect across sheets too. So really, what you have is a 3D lattice of magnetically-active irregularities in otherwise diamagnetic graphite!

No wonder graphite has such complex magnetic properties. 🙂

Impurities & allotropes muddle the magnetism

Aside from built-in defects, foreign elements can also introduce magnetism. For example, adding boron or nitrogen leaves spare electrons that enable ferromagnetism.

This doping effect is important because raw graphite contains lots of impurities. Dust, clay, tiny metal particles – they all impact the magnetic response.

That’s why different graphite sources feel more or less magnetic. Impurity levels vary unpredictably, so magnetism depends largely on the specific sample.

Complicating matters further, graphite has structural varieties called allotropes. Graphene (single layers), nanotubes, buckyballs, charcoal, diamond…all share properties like conductivity despite their unique structures.

And because geometry dictates a material’s electronic configuration, each carbon allotrope interacts with magnetism differently:

• Diamond – nonmagnetic
• Graphene – intrinsic quantum magnetism
• Nanotubes – variable magnetism from defects
• Buckyballs – diamagnetic
• Amorphous carbon – complex magnetism from impurities

So “Is graphite magnetic?” isn’t really the best question. The answer depends on which graphite you mean!

No wonder it’s such a confusing topic. 🙂

External factors bend graphite’s magnetism

Aside from built-in features like defects and geometry, external influences also modify graphite’s magnetism.

For one thing, scientists found they can induce ferromagnetism by irradiating graphite with protons. The radiation displaces carbon atoms, leaving defects that couple magnetically. Pretty wild!

Temperature also alters graphite’s diamagnetism, though not by much. Turns out thermal energy easily overcomes the weak magnetic coupling between layers.

That said, extremely high temps (think arc furnace) do impact graphite’s electron configuration. So while everyday temperatures bring negligible change, extreme heat tweaks the magnetic response somewhat.

The last external magnetism-modifier is simply applying an external magnetic field. Even a fridge magnet can induce a slight opposing field in graphite thanks to diamagnetism.

Strong laboratory fields amplify this effect. But the induced field remains comparatively tiny and temporary – graphite doesn’t become permanently magnetic like iron.

Advances enable magnetic graphite

The good news is scientists are finding ways to get around graphite’s fickle magnetism. Clever chemical modification is one route…

For example, researchers at Rice University turned graphite magnetic by attaching hydroxyl groups. Their compound (fluorographene) maintained magnetism even at scorching temperatures – definitely not typical graphite behavior!

Fluorographene lattice – Credit A.G. Rajan et. al (10.1021/jacs.6b12239)

Meanwhile, others found irradiating graphene makes it magnetic too.

Approaches like proton-zapping graphene are unlikely to work at scale. But at the research level, they show graphite can be forced magnetic with enough creativity.

Conclusion: It’s…complicated!

So in summary – is graphite magnetic?

The nickel tour tells us it’s diamagnetic and generally non-magnetic. And based on the structure of orderly graphite crystals, that’s an accurate assessment.

But peer closer and you uncover all kinds of complexities:

• Defects in the lattice induce magnetism locally
• Some layer orientations couple magnetically
• Impurities lend ferromagnetism through extra electrons
• Allotrope geometry causes unexpected effects
• External factors like heat and magnets add influence

And despite the headaches that complex system brings, scientists are finding ways to make graphite attracted to magnets…at least in the lab.

So while everyday graphite isn’t tremendously magnetic, the true story has a lot of nuance. Graphite’s relationship with magnetism is actually rich and fascinatingly complex!