Bismuth is magnetic, but not in the way most people mean when they ask. It is the strongest naturally occurring diamagnetic element, which means it actively repels magnetic fields rather than being attracted to them the way iron or nickel would be. Place a chunk of bismuth near a magnet and it pushes away. This behavior, while subtle, has made bismuth one of the most studied elements in physics and an increasingly useful material in sensor technology and quantum research.
How Bismuth Responds to a Magnet
Most people picture magnetism as attraction: a magnet sticks to your refrigerator door, a compass needle swings toward north. That kind of behavior belongs to ferromagnetic and paramagnetic materials, where the internal structure of the material lines up with an external magnetic field. Bismuth does the opposite. When you bring a magnet near a piece of bismuth, the electrons in bismuth generate tiny currents that create their own magnetic field pointing the other way. The result is a gentle but measurable repulsion.
This makes bismuth the strongest diamagnetic element found in nature, a distinction researchers at Argonne National Laboratory have used as a benchmark when searching for new materials with extreme diamagnetic properties.1Argonne National Laboratory. Dialing-Up Diamagnetism to Search for a New Material The repulsion is not strong enough that you would feel it by holding a bismuth crystal near a fridge magnet. But under the right conditions, with strong enough magnets and lightweight enough objects, the effect becomes dramatic.
The Levitation Trick
One of the most eye-catching demonstrations of bismuth’s diamagnetism involves levitation. A small permanent magnet can be suspended in midair between two plates of bismuth, floating without any power source or mechanical support. This seems like it should be impossible. A physics result known as Earnshaw’s theorem says you cannot stably levitate one magnet using only other magnets under normal conditions. But diamagnetic materials sidestep that restriction. When bismuth is placed in the right positions around a magnet, the repulsive force it generates creates a stable energy well that traps the magnet in place.2American Journal of Physics. Diamagnetically stabilized magnet levitation
Both bismuth and graphite have been used in these levitation setups, and researchers have measured the diamagnetic properties of both to see how effectively each one can stabilize a floating magnet.3American Journal of Physics. Diamagnetically stabilized magnet levitation Graphite is a strong diamagnet in its own right, but bismuth’s advantage is that it is a dense metal with consistent properties throughout its bulk, which can make experimental setups more straightforward. If you have ever seen videos of small magnets hovering between shiny, stair-step-shaped bismuth crystals, this is exactly what is happening.
How Faraday First Noticed
The discovery of diamagnetism itself is tied directly to bismuth. In November 1845, Michael Faraday announced to the Royal Society that he had found a new and very weak magnetic property of matter. He noticed that certain substances, rather than being drawn toward a magnet’s poles, were pushed away. A bar of such material placed between the poles of a magnet would swing around and settle perpendicular to the line between the poles, the exact opposite of what a magnetic substance like iron does.4PubMed Central. John Tyndall and the Early History of Diamagnetism
Bismuth stood out early on. A researcher named Le Bailif appears to have been the first to note the comparatively great strength of bismuth’s diamagnetism.5PubMed Central. John Tyndall and the Early History of Diamagnetism Faraday himself described the repulsion from a single pole as “remarkably like a case of weak electrostatic repulsion.” Nearly two centuries later, bismuth remains the go-to example whenever physicists explain what diamagnetism is and how it differs from the more familiar attraction of ferromagnets.
When Bismuth Compounds Become Genuinely Magnetic
Pure bismuth repels magnets. But alloy bismuth with the right elements and the story changes completely. Manganese-bismuth (MnBi) alloys are a striking example. Pure manganese is paramagnetic at room temperature, meaning it has a weak, temporary attraction to magnets. But when combined with bismuth, the resulting alloy can become ferromagnetic, antiferromagnetic, or ferrimagnetic depending on the composition and preparation.6Next Materials. Recent development on magnetic properties of MnBi alloys MnBi alloys have attracted attention as potential rare-earth-free permanent magnets, which is a significant practical motivation given the supply-chain pressures on conventional rare-earth magnets.
Bismuth ferrite, or BiFeO₃, is another well-studied compound. It is one of the few materials that is simultaneously ferroelectric and antiferromagnetic at room temperature, a combination that makes it useful in memory devices and sensors. Calculations show that the antiferromagnetic phase is energetically more favorable than the ferromagnetic phase, with magnetization preferring a particular crystal axis.7PubMed Central. First-Principles Investigation of Structural, Electronic, and Magnetic Properties of BiFeO3 and Bi2Fe4O9 Nanostructures So while bismuth atoms on their own are diamagnetic, they can participate in crystal structures that produce robust magnetism when paired with elements like iron or manganese. The bismuth is not just along for the ride; its heavy atoms and large electron cloud influence the magnetic behavior of these compounds in ways lighter elements cannot replicate.
Bismuth as a Magnetic Field Sensor
Bismuth’s relationship with magnetism has a practical side that goes well beyond levitation demos. The element has unusually high magnetoresistance, meaning its electrical resistance changes a lot when you apply a magnetic field. At higher fields, bulk bismuth’s magnetoresistance can actually exceed that of the multilayer structures used in giant magnetoresistance (GMR) devices. This happens because bismuth’s electrons have an extremely low effective mass compared to other metals, which gives them a mean free path on the order of micrometers, far longer than in typical metals and second only to graphene.8ResearchGate. Bismuth-based flexible magnetic sensor
Bismuth-based Hall sensors exploit this sensitivity. The Hall effect, where a voltage develops across a conductor carrying current in a magnetic field, is particularly strong in bismuth because of those same unusual electron properties. Bismuth Hall sensors have been developed and tested at fields up to seven tesla for the ITER fusion reactor project, where they would serve as part of the steady-state magnetic diagnostic system.9PubMed. High magnetic field test of bismuth Hall sensors for ITER steady state magnetic diagnostic In a fusion reactor, accurately measuring the magnetic field that confines superheated plasma is not optional; it is essential for the machine to operate at all. Bismuth’s combination of strong Hall response and high magnetoresistance even at room temperature makes it a serious candidate for such demanding environments.
Bismuth also presents an unusually large Nernst coefficient, which relates to the voltage generated across a material when a magnetic field and a temperature gradient are applied simultaneously. This Nernst effect in bismuth is much larger than what has been found in correlated metals, adding yet another way bismuth converts magnetic information into an electrical signal.10PubMed. Nernst effect in semimetals: the effective mass and the figure of merit
Reaching the Quantum Limit With Modest Magnets
One of the reasons physicists keep returning to bismuth is that it enters exotic quantum states in magnetic fields that are readily achievable in a laboratory. In most metals, reaching the so-called quantum limit, where the electrons are confined to their lowest energy levels by the magnetic field, would require impractically strong fields. Bismuth’s electrons have such a long quantum wavelength that a moderate field of a few tesla is enough to push the material into this regime.11PubMed. Signatures of electron fractionalization in ultraquantum bismuth
Once there, bismuth behaves in ways that challenge standard descriptions of how electrons move through solids. Researchers have observed signatures that suggest electron fractionalization, a phenomenon more commonly associated with esoteric quantum systems than with a metal you can buy online. The Landau spectrum of bismuth in the extreme quantum limit turns out to be complex, with many lines that shift depending on the angle between the crystal and the magnetic field. Studies of high-purity bismuth crystals have mapped this spectrum in detail, revealing features linked to twin boundaries within the crystal structure.12PubMed Central. Landau spectrum and twin boundaries of bismuth in the extreme quantum limit None of this makes bismuth “magnetic” in everyday language, but it means the element’s electrons are extraordinarily responsive to magnetic fields in ways that probe deep questions about how matter behaves.
Superconductivity Just Above Absolute Zero
Bismuth held out as a non-superconductor for a very long time. Researchers suspected it might superconduct, but nobody could prove it because the transition temperature is absurdly low. In 2016, a team finally found bulk superconductivity in pure bismuth single crystals at just 0.53 millikelvin, roughly half a thousandth of a degree above absolute zero, under ambient pressure. The estimated critical magnetic field was only about 5.2 microtesla at zero kelvin.13PubMed. Evidence for bulk superconductivity in pure bismuth single crystals at ambient pressure
Superconductors famously expel magnetic fields from their interior, a phenomenon known as the Meissner effect. So at this vanishingly low temperature, bismuth flips from being the strongest natural diamagnet to being a perfect diamagnet: it does not just resist a magnetic field, it excludes it entirely. The catch is that this only happens under conditions so extreme they are irrelevant to any practical application. The critical field of 5.2 microtesla is roughly a tenth of Earth’s own magnetic field, which means even our planet’s background magnetism would be enough to destroy bismuth’s superconducting state. The discovery matters more for what it tells physicists about semimetals and pairing mechanisms than for any foreseeable technology.
Bismuth in Topological Insulators and Spintronics
Bismuth-based compounds have become stars of a different branch of physics: topological materials. Compounds like Bi₂Se₃ and Bi₂Te₃ are topological insulators, meaning they are insulating in their interior but conduct electricity along their surfaces through special states where the electron’s spin is locked to its direction of travel. Researchers have demonstrated that these surface states are nearly 100 percent spin-polarized, with a one-to-one relationship between the electron’s momentum and its spin orientation.14Nature. First observation of Spin-Momentum Helical Locking in Bi2Se3 and Bi2Te3, demonstration of Topological-Order at 300K and a realization of topological-transport-regime This topological order persists at room temperature, which is unusual and practically important.
The spin-momentum locking in these materials has drawn serious attention in the spintronics community. Because the spin direction is dictated by the direction of current flow, a charge current on the surface of a topological insulator automatically generates a spin current. Ultrathin films of Bi₁₋ₓSbₓ alloys have been studied as topological insulators with ultrafast spin-charge conversion properties.15PubMed Central. Spin-Momentum Locking and Ultrafast Spin-Charge Conversion in Ultrathin Epitaxial Bi(1 – x) Sb(x) Topological Insulator In a spintronic device, you want to write, read, and manipulate magnetic information using spin currents rather than brute-force magnetic fields. Bismuth-based topological insulators offer a particularly efficient pathway to do that because the surface electrons are almost perfectly spin-polarized by nature, no external magnetic field required.
The irony is worth appreciating: bismuth, the classic antimagnetic material, has become one of the most important elements in the emerging field of spin-based electronics. Its value comes precisely from its unusual electronic structure, the same properties that make it strongly diamagnetic in bulk also produce the exotic surface states that spintronics researchers want to exploit.
Bismuth’s Nuclear Spin
Bismuth has one more magnetic dimension that rarely comes up in casual discussions. Its only stable isotope, bismuth-209, has a nuclear spin of 9/2, which is quite high. This makes it detectable by nuclear magnetic resonance techniques, the same physics behind MRI machines. Bismuth-209 has high natural abundance and a moderately high resonance frequency, but it also has a large nuclear electric quadrupole moment, which complicates experiments because the nucleus interacts strongly with surrounding electric field gradients.16PubMed. Solid-state nuclear magnetic resonance of spin-9/2 nuclei (115) In and (209) Bi in functional inorganic complex oxides
Solid-state NMR of bismuth-209 is technically challenging but has been carried out in complex oxides and other functional materials. The information it provides is different from what bulk magnetism measurements tell you. Nuclear spin probes the local electronic environment around individual bismuth atoms, revealing details about bonding, symmetry, and disorder that other techniques miss. So even at the nuclear level, bismuth has a nontrivial relationship with magnetism, one that researchers continue to find useful for characterizing new bismuth-containing materials as they are developed for everything from catalysis to quantum computing.