# How Magnets Work > In 2026 the European Physical Society gave its Europhysics Prize to three physicists for altermagnetism, which it describes as a third basic kind of magnetic order. To see why that matters, this film goes back to the beginning: the lodestone and the compass, Gilbert's little Earth, Ørsted's current, the electromagnet, the electron's spin, why paired electrons cancel, how iron's domains line up and how heat destroys them, antiferromagnets, the magnets inside motors, MRI scanners and hard drives, and finally the altermagnet. Cut a magnet in half, switch a current on, magnetise iron, heat it past its Curie point and switch between three kinds of magnetic order. Interactive film: https://www.planetpast.com/stories/how-magnets-work/ Publisher: PlanetPast (https://www.planetpast.com/) · d => T('readPublished', l, { d: dateIn(d, l) }) 2026-10-20 · Physics, Technology ## Prologue ### A third kind of magnet *Prologue* An old force, a new discovery. Why does a piece of iron stick to a magnet, while a plastic spoon does not? And why does a compass needle point north? In 2026 the European Physical Society gave its Europhysics Prize to three physicists for what it calls a third basic kind of magnetic order: altermagnetism. To see why that matters, we start at the beginning. ![Each arrow stands for one atom’s tiny magnet. AI-generated still.](https://assets.planetpast.com/a/79/792c6edbfd7a5fb6.jpg) - Jairo Sinova, University of Mainz - Libor Šmejkal, Max Planck institutes in Dresden - Tomas Jungwirth, Czech Academy of Sciences - **2**: families known for a century (ferro, antiferro) - **3**: families now Prologue · The news #### The 2026 Europhysics Prize Johannes Gutenberg University Mainz reports that the Condensed Matter Division of the European Physical Society awarded the 2026 Europhysics Prize, given since 1975, to Jairo Sinova (Mainz), Libor Šmejkal (Max Planck Institutes for the Physics of Complex Systems and for Chemical Physics of Solids, and the Czech Academy of Sciences) and Tomas Jungwirth (Institute of Physics of the Czech Academy of Sciences and the University of Nottingham), for altermagnetism, which the university describes as a third elementary form of collinear magnetism alongside ferromagnetism and antiferromagnetism. The prize was announced in July 2026 and presented in Graz in September; ScienceDaily carried the release on 18 October 2026. How to use: pick a chapter or press ← →; drag to rotate. Several steps have buttons you can press. The 3D atoms, arrows, field lines and filings are simplified teaching models, not to scale. Sources: [Johannes Gutenberg University Mainz: 2026 Europhysics Prize honors discovery of a third fundamental class of magnetism](https://press.uni-mainz.de/2026-europhysics-prize-honors-discovery-of-a-third-fundamental-class-of-magnetism/); [ScienceDaily (18 Oct 2026), from Mainz University: the Europhysics Prize for altermagnetism](https://www.sciencedaily.com/releases/2026/10/261017230035.htm) ## Chapter I · The stone that points ### The lodestone *Chapter I · The stone that points* A rock that pulls on iron and turns to face north. It begins with a stone. Lodestone is a piece of the mineral magnetite that nature has magnetised, most likely by lightning. It pulls on iron. In China, in 1088, the scholar Shen Kuo described needles rubbed on lodestone. Hung from a silk thread, they settled along the north–south line. A few decades later, Zhu Yu recorded sailors steering in dark weather by a south-pointing needle. ![Most lodestones are found near the surface, which fits the lightning idea. AI-generated still.](https://assets.planetpast.com/a/06/06c8103f185c919d.jpg) ![A magnetised needle free to turn settles along the north–south line. AI-generated still.](https://assets.planetpast.com/a/3a/3a52797e5deba6d9.jpg) - 1088: Shen Kuo, Dream Pool Essays - 1111–1117: Zhu Yu: pilots use the needle at sea - c. 1190: Alexander Neckam, England Chapter I · The stone that points #### Lodestone and the first compasses Lodestones are naturally magnetised pieces of the mineral magnetite; the leading theory is that they are magnetised by the strong fields around lightning bolts, which fits their mostly near-surface location. The first incontestable Chinese reference to a magnetised needle is Shen Kuo’s Dream Pool Essays of 1088. Zhu Yu’s Pingzhou Table Talks (1111–1117) records pilots using a south-pointing needle in dark weather, the earliest explicit record of the compass at sea. In Europe, Alexander Neckam described a compass needle around 1190. The 3D atoms, arrows, field lines and filings are simplified teaching models, not to scale. Sources: [Wikipedia: Lodestone](https://en.wikipedia.org/wiki/Lodestone); [Wikipedia: History of the compass](https://en.wikipedia.org/wiki/History_of_the_compass) ### A little Earth *Chapter I · The stone that points* Why a needle points north at all. But why should a needle point north? In 1600 the English physician William Gilbert published De Magnete, On the Magnet. He shaped a lodestone into a ball, a little Earth, and moved a tiny needle over it. The needle pointed to the poles and dipped downward. His conclusion: the Earth itself is a giant magnet. Today we know why. Molten metal churning in Earth's outer core carries electric currents, and those currents make the field. ![Gilbert called the ball a terrella, “little Earth”, and his needle a versorium. AI-generated still.](https://assets.planetpast.com/a/d7/d7c4505e4abbe823.jpg) - written in Latin, in six books - the dip of the needle had been found by Robert Norman in 1581 - Gilbert became physician to Elizabeth I in 1601 ![About 97–99% of the field at the surface comes from the liquid outer core (NASA). AI-generated illustration.](https://assets.planetpast.com/a/b6/b691e1d5a0269bc3.jpg) - **~20,000 nT**: at the magnetic equator - **~65,000 nT**: near the poles Chapter I · The stone that points #### Gilbert and the geodynamo William Gilbert (1544–1603), later physician to Elizabeth I, published De Magnete in London in 1600. Moving a small needle over a spherical lodestone he called a terrella, he found it pointed to the poles and dipped as compasses do, and concluded that the Earth itself is a giant magnet. NASA explains that the main field is produced by electric currents driven by a self-sustaining dynamo in Earth’s conducting liquid outer core; it supplies about 97–99% of the field at the surface, roughly 20,000 nT (nanotesla) at the magnetic equator and 65,000 nT near the poles. Geographic and magnetic poles are not in exactly the same place; the 3D globe simplifies this. The 3D atoms, arrows, field lines and filings are simplified teaching models, not to scale. Sources: [NASA Goddard (D. P. Stern): William Gilbert and De Magnete](https://pwg.gsfc.nasa.gov/earthmag/DMGRev2.htm); [NASA Goddard: the core (main) magnetic field of the Earth](https://core2.gsfc.nasa.gov/terr_mag/core.html) ## Chapter II · Fields and currents ### Poles never come alone *Chapter II · Fields and currents* Every magnet carries an invisible field. Every magnet is surrounded by a magnetic field, a region where it can push and pull on iron. Iron filings line up along curves called field lines. The lines leave one end, the north pole, loop around, and enter the other end, the south pole. Opposite poles attract; like poles repel. Poles never come alone. Cut a magnet in half and you get two smaller magnets, each with its own north and south. Try it. ![Each filing becomes a tiny magnet and turns to lie along the field. AI-generated still.](https://assets.planetpast.com/a/06/06c19677f1704b84.jpg) - form closed loops, continuing inside the magnet - crowd together where the field is strong - never cross one another - **0**: isolated poles ever found - **2**: poles in every piece Chapter II · Fields and currents #### Magnetic fields and poles The NCERT physics textbook states that the field lines of a magnet form continuous closed loops, that iron filings sprinkled around a bar magnet show its two poles, and that, unlike electric charges, isolated north and south poles (magnetic monopoles) do not exist: a bar magnet broken in two gives two similar, slightly weaker magnets. A freely suspended magnet’s north-seeking end points towards geographic north. The 3D atoms, arrows, field lines and filings are simplified teaching models, not to scale. Sources: [NCERT Physics, Class 12, chapter 5: Magnetism and Matter (PDF)](https://blog.mtg.in/wp-content/uploads/2023/05/leph105.pdf) ### Ørsted’s needle *Chapter II · Fields and currents* Electricity and magnetism turn out to be one thing. For centuries, electricity and magnetism seemed unrelated. Then, on 21 April 1820, during a lecture in Copenhagen, Hans Christian Ørsted switched on a current, and a nearby compass needle swung. An electric current makes a magnetic field. Around a straight wire, the field lines are circles, like rings around the wire. Switch the current off and the field is gone. Reverse it, and the needles turn the other way. Try the switch. ![The needle moved so little that the audience did not notice (APS). AI-generated still.](https://assets.planetpast.com/a/9f/9ff6d17827fc7c3b.jpg) - 21 Apr 1820: Ørsted sees the needle move - 21 Jul 1820: he publishes in a pamphlet - 1820s: Ampère writes the mathematics of forces between currents - no current: no field - more current: stronger field - reverse the current: reverse the field Chapter II · Fields and currents #### Ørsted, 1820 APS News: on 21 April 1820, while setting up a lecture demonstration in Copenhagen, Hans Christian Ørsted noticed that a compass needle moved away from magnetic north when he switched on an electric current. The effect was small and the audience did not notice. He published on 21 July 1820. André-Marie Ampère soon worked out a mathematical law for the magnetic forces between current-carrying wires; about a decade later, Michael Faraday showed the reverse effect, a changing magnetic field inducing a current. The 3D atoms, arrows, field lines and filings are simplified teaching models, not to scale. Sources: [APS News: July 1820, Oersted and electromagnetism](https://aps.org/apsnews/2008/07/1820-oersted-electromagnetism) ### The electromagnet *Chapter II · Fields and currents* Coil the wire, add iron, switch it on. Wind the wire into a coil, and the rings add up into a field shaped just like a bar magnet's. Slide iron inside, and the field becomes thousands of times stronger. In 1824 William Sturgeon built such an electromagnet in England. It lifted about four kilograms. Joseph Henry's soon held over nine hundred. An electromagnet is a magnet with a switch: turn it on and the iron block jumps up. ![Sturgeon’s first one had about 18 turns of bare copper wire on a bent iron bar. AI-generated still.](https://assets.planetpast.com/a/d1/d1a9c9b58388a20b.jpg) - Sturgeon, 1825 report: ~4 kg - Joseph Henry, 1830s: 936 kg - cranes that lift scrap steel - relays, bells and loudspeakers - the coils of electric motors Chapter II · Fields and currents #### The electromagnet A current through a coil makes a field concentrated along its axis; an iron core makes it thousands of times stronger than the coil alone, and the field disappears when the current stops. William Sturgeon made the first electromagnet in 1824: a horseshoe of iron with about 18 turns of bare copper wire. In 1825 he reported that the seven-ounce (about 200 g) magnet lifted nine pounds (about 4 kg). From 1830 Joseph Henry used silk-insulated wire with many more turns; one of his magnets supported 2,063 lb (936 kg). The 3D atoms, arrows, field lines and filings are simplified teaching models, not to scale. Sources: [Wikipedia: Electromagnet (Sturgeon 1824, Henry)](https://en.wikipedia.org/wiki/Electromagnet) ## Chapter III · Inside the atom ### Tiny magnets everywhere *Chapter III · Inside the atom* A lodestone has no wires. So where are its currents? But a lodestone has no wires. Where does its magnetism come from? From inside its atoms. Every atom holds electrons, tiny particles with negative charge. An electron moving around its atom is like a minute loop of current. Each electron also has a built-in property called spin, which makes it a tiny bar magnet in its own right. Such a tiny magnet is called a magnetic moment. ![Electrons form a cloud around a nucleus far smaller than the atom. AI-generated illustration.](https://assets.planetpast.com/a/e6/e6c235f90dbb7f06.jpg) - orbital motion of the electrons - the electrons’ intrinsic spin - the name is historical - a quantum property every electron always has, like its charge - measured along a direction, it is either “up” or “down” Chapter III · Inside the atom #### The electron as a magnet LibreTexts: the magnetism of metals and other materials is determined by the orbital and spin motions of their unpaired electrons; the electron’s magnetic dipole moment is generated by its intrinsic spin. In the 3D model the large arrow through the orbit shows the moment of the orbital motion, the small arrow on the electron its spin. Electrons do not really move in neat circles; the orbit is a classroom picture. The 3D atoms, arrows, field lines and filings are simplified teaching models, not to scale. Sources: [LibreTexts Chemistry: magnetic properties of materials](https://chem.libretexts.org/Courses/Saint_Marys_College_Notre_Dame_IN/CHEM_431%3A_Inorganic_Chemistry_%28Haas%29/CHEM_431_Readings/14%3A_Magnetism/14.02%3A_Magnetic_Properties_of_Materials) ### Why most things are not magnets *Chapter III · Inside the atom* Electrons like to pair up, back to back. If every electron is a magnet, why isn't everything magnetic? Because electrons usually come in pairs, with their spins pointing opposite ways. The two tiny magnets cancel. In water, wood or plastic, nearly every electron has a partner, so they barely react to a magnet. But iron, cobalt and nickel keep several unpaired electrons, so each of their atoms is a small magnet. Still, that alone does not make a magnet. - one spin up, one spin down - their fields cancel - the material is weakly pushed away by a magnet (diamagnetic) - all electrons paired: 0 - iron atom: unpaired electrons: 4 - **Fe**: iron - **Co**: cobalt - **Ni**: nickel Chapter III · Inside the atom #### Paired and unpaired electrons LibreTexts: diamagnetic substances are characterised by paired electrons, whose magnetic fields cancel; they are weakly repelled by a magnetic field. An atom with one or more unpaired electrons is paramagnetic and is attracted to a field. HyperPhysics names iron, nickel, cobalt and some rare earths (gadolinium, dysprosium) as ferromagnetic. An isolated iron atom has four unpaired electrons, as the chart shows; in solid iron the figure per atom is smaller. The 3D atoms, arrows, field lines and filings are simplified teaching models, not to scale. Sources: [LibreTexts Chemistry: magnetic properties of materials](https://chem.libretexts.org/Courses/Saint_Marys_College_Notre_Dame_IN/CHEM_431%3A_Inorganic_Chemistry_%28Haas%29/CHEM_431_Readings/14%3A_Magnetism/14.02%3A_Magnetic_Properties_of_Materials); [HyperPhysics (Georgia State University): ferromagnetism](https://www.hyperphysics.gsu.edu/hbase/solids/ferro.html) ## Chapter IV · Order in iron ### Neighbours that agree *Chapter IV · Order in iron* How a plain iron nail becomes a magnet. In iron, something more happens. A quantum effect with no everyday equivalent, the exchange interaction, makes the spins of neighbouring atoms line up the same way. This is ferromagnetism. Atoms that agree form regions called magnetic domains. In an ordinary nail, the domains point every which way, and cancel each other out. Bring a magnet near, and the domains already lined up with its field grow and swallow their neighbours. Now the nail is a magnet. Press apply field. - diamagnetic: weakly pushed away (water, wood) - paramagnetic: weakly pulled, no order - ferromagnetic: spins lock together ![Domains are about 0.1 mm to a few millimetres across (HyperPhysics). AI-generated still.](https://assets.planetpast.com/a/f1/f126ea770062ba25.jpg) - **0.0002**: tesla applied (tesla: unit of field strength) - **~1**: tesla inside the iron Chapter IV · Order in iron #### Ferromagnetism and domains HyperPhysics: in ferromagnets a quantum-mechanical interaction locks the moments of neighbouring atoms into parallel order, so unpaired electron spins line up within regions called domains, about 0.1 mm to a few mm across. In an external field, domains already aligned with it grow at the expense of their neighbours; in annealed iron an applied field of about 0.0002 T (tesla) can produce about 1 T. LibreTexts names this coupling the exchange interaction. Tesla (T) is the unit of magnetic field strength. Earth’s field is about 0.00005 T. The 3D atoms, arrows, field lines and filings are simplified teaching models, not to scale. Sources: [HyperPhysics (Georgia State University): ferromagnetism](https://www.hyperphysics.gsu.edu/hbase/solids/ferro.html); [LibreTexts Chemistry: magnetic properties of materials](https://chem.libretexts.org/Courses/Saint_Marys_College_Notre_Dame_IN/CHEM_431%3A_Inorganic_Chemistry_%28Haas%29/CHEM_431_Readings/14%3A_Magnetism/14.02%3A_Magnetic_Properties_of_Materials) ### The Curie point *Chapter IV · Order in iron* Heat a magnet enough and it forgets. Heat fights that order. As iron gets hotter, its atoms jiggle harder, and the spins wobble out of line. At about 770 degrees Celsius, iron's Curie temperature, named after Pierre Curie, the order collapses. The domains vanish, and iron stops being ferromagnetic. Cool it again and the domains return, but pointing at random. The magnet has been wiped. Try heating it yourself. ![Iron glows red at temperatures not far below its Curie point. AI-generated still.](https://assets.planetpast.com/a/75/75b6c38d90088638.jpg) - nickel: 354 °C - neodymium magnets: 310–400 °C - iron: 770 °C - cobalt: 1,130 °C - moments point at random - the metal is only weakly attracted (paramagnetic) - Pierre Curie measured the transition in 1895 Chapter IV · Order in iron #### The Curie temperature Above its Curie temperature a ferromagnet loses its permanent magnetism and becomes paramagnetic: its moments are disordered, so it is non-magnetic without an applied field. The temperature is named after Pierre Curie, who studied the transition in 1895. Values listed on Wikipedia: iron 770 °C (1043 K, also given by HyperPhysics), cobalt 1130 °C, nickel 354 °C, neodymium magnets 310–400 °C. Temperatures on the buttons are illustrative steps; the arrows are a toy model. The 3D atoms, arrows, field lines and filings are simplified teaching models, not to scale. Sources: [Wikipedia: Curie temperature](https://en.wikipedia.org/wiki/Curie_temperature); [HyperPhysics (Georgia State University): ferromagnetism](https://www.hyperphysics.gsu.edu/hbase/solids/ferro.html) ### The hidden magnets *Chapter IV · Order in iron* Order that cancels itself out. Spins can also be ordered another way. In some materials, such as chromium, the exchange interaction makes neighbours point in opposite directions: up, down, up, down. This is antiferromagnetism. In 1970 the French physicist Louis Néel shared the Nobel Prize in Physics for his work on it. Its opposite spins cancel exactly, so from outside it looks unmagnetic. For a century, magnets whose spins lock into order came in just these two families. Compare them. ![Each atom is still a magnet; only the total is zero. AI-generated still.](https://assets.planetpast.com/a/f6/f6a5e449557a259a.jpg) > for fundamental work and discoveries concerning antiferromagnetism and ferrimagnetism (Nobel Prize citation for Louis Néel, 1970 (shared with Hannes Alfvén)) - ferromagnet: spins parallel; strong net magnet - antiferromagnet: spins alternate; net zero Chapter IV · Order in iron #### Antiferromagnetism In an antiferromagnet a negative exchange interaction between neighbouring atoms (LibreTexts gives body-centred cubic chromium as the example) makes their moments point in opposite directions, so the magnetisation is compensated; above the Néel temperature the material becomes paramagnetic. Louis Néel shared the 1970 Nobel Prize in Physics with Hannes Alfvén, “for fundamental work and discoveries concerning antiferromagnetism and ferrimagnetism”. Mainz University and ScienceDaily note that for over 100 years collinear magnets were sorted into these two categories. The 3D atoms, arrows, field lines and filings are simplified teaching models, not to scale. Sources: [LibreTexts Chemistry: magnetic properties of materials](https://chem.libretexts.org/Courses/Saint_Marys_College_Notre_Dame_IN/CHEM_431%3A_Inorganic_Chemistry_%28Haas%29/CHEM_431_Readings/14%3A_Magnetism/14.02%3A_Magnetic_Properties_of_Materials); [NobelPrize.org: the Nobel Prize in Physics 1970](https://www.nobelprize.org/prizes/physics/1970/summary/); [ScienceDaily (18 Oct 2026), from Mainz University: the Europhysics Prize for altermagnetism](https://www.sciencedaily.com/releases/2026/10/261017230035.htm) ## Chapter V · Magnets at work ### Motors, magnets and scanners *Chapter V · Magnets at work* Where the strongest magnets go to work. An electric motor turns because the current in its coils pushes against a magnet's field. Motors use about half of the world's electricity. In 1984, General Motors and Sumitomo each developed neodymium magnets. They are the strongest permanent magnets on sale, used in many electric cars and wind turbines. Hospital MRI scanners use giant superconducting electromagnets to line up hydrogen nuclei in the body. A radio pulse tips them, and the signal they send back becomes the image, without X-rays. ![Copper windings on the outside, curved permanent magnets on the rotor. AI-generated still.](https://assets.planetpast.com/a/de/dea21d42f9d98c0d.jpg) ![Some turbine generators use permanent neodymium magnets instead of field coils. AI-generated still.](https://assets.planetpast.com/a/29/2968af8e4add47e5.jpg) $$\mathrm{Nd_2Fe_{14}B}$$ - $\mathrm{Nd}$: neodymium, a rare-earth metal - $\mathrm{Fe}$: iron, which carries most of the magnetism - $\mathrm{B}$: boron - **0.00005 T**: Earth’s field, roughly - **1.5 T**: most MRI scanners: superconducting coils, no resistance when very cold - **3 T**: stronger MRI systems Chapter V · Magnets at work #### Magnets at work Electric motors produce torque from the interaction between a magnetic field and the current in a wire winding, and consume about 50% of the world’s electricity. Neodymium magnets, an alloy forming the Nd₂Fe₁₄B crystal, were developed independently in 1984 by General Motors and Sumitomo Special Metals; they are the strongest permanent magnets commercially available and are used in hybrid and electric vehicle drive motors, some wind turbine generators, hard-disk head actuators and headphones. Most clinical MRI systems operate at 1.5 T, with 3 T systems also common; most use superconducting magnets cooled by liquid helium. The field aligns hydrogen nuclei, a radio pulse tips them, and the signal they give back is turned into an image (National MagLab); MRI uses no ionising radiation. The motor in 3D is a simplified model, not a real design. This is general education about how the machines work, not medical advice. Sources: [Wikipedia: Electric motor](https://en.wikipedia.org/wiki/Electric_motor); [Wikipedia: Neodymium magnet](https://en.wikipedia.org/wiki/Neodymium_magnet); [Wikipedia: Magnetic resonance imaging](https://en.wikipedia.org/wiki/Magnetic_resonance_imaging); [National MagLab: how MRI works (interactive tutorial)](https://nationalmaglab.org/magnet-academy/watch-play/interactive-tutorials/magnetic-resonance-imaging-mri/) ### Reading with spin *Chapter V · Magnets at work* A Nobel Prize that went inside hard drives. A hard drive stores data as tiny magnetised patches on a spinning disk. One direction means one, the other means zero. From 1997, drives read them using an effect found in 1988 by Albert Fert and Peter Grünberg: giant magnetoresistance. In very thin layers of metal, a tiny change in magnetism makes a big change in electrical resistance. It works because electrons carry spin as well as charge. The pair shared the 2007 Nobel Prize; since about 2005 a related spin effect has taken over. Electronics that uses spin is called spintronics. ![The read head flies just above the platter without touching it. AI-generated still.](https://assets.planetpast.com/a/59/59838b342af921e4.jpg) - 1988: Fert and Grünberg find GMR independently - 1997: first GMR read head - 2005: TMR heads begin to replace GMR - 2007: Nobel Prize in Physics ![Bits lie along circular tracks under a head that never touches the disk. AI-generated illustration.](https://assets.planetpast.com/a/7d/7d0f2e3b0ffcffa3.jpg) - **1997–2005**: GMR heads - **2005 on**: TMR heads, also spin-based Chapter V · Magnets at work #### Hard drives and giant magnetoresistance The 2007 Nobel Prize in Physics went to Albert Fert and Peter Grünberg “for the discovery of Giant Magnetoresistance”, which each found independently in 1988: very small magnetic changes give rise to large differences in electrical resistance. A GMR read-out head converts the disk’s tiny magnetic patterns into changes in current, the ones and zeros of the data. The first such head was launched in 1997 and quickly became standard; the press release calls GMR one of the first real applications of nanotechnology. GMR depends on the spin of the conducting electrons. A UK research impact case study reports that GMR heads were used from 1997 until 2005 and were then gradually replaced by heads based on tunnel magnetoresistance (TMR), another effect that depends on electron spin. The 3D atoms, arrows, field lines and filings are simplified teaching models, not to scale. Sources: [NobelPrize.org: press release, the Nobel Prize in Physics 2007](https://www.nobelprize.org/prizes/physics/2007/press-release/); [UK REF impact case study: magnetic tunnel junction read heads (GMR used 1997–2005, then TMR)](https://impact.ref.ac.uk/CaseStudies/CaseStudy.aspx?Id=42270) ## Chapter VI · A third kind ### Cancelled, yet split *Chapter VI · A third kind* A magnet with no net field that still sorts electrons by spin. Which brings us back to the prize. From 2019, Šmejkal, Sinova, Jungwirth and colleagues used the symmetries of crystals to predict a third kind of order. In an altermagnet, neighbouring spins point opposite ways, so, like an antiferromagnet, it has no overall magnetism. But the two sets of atoms sit in the crystal at different angles. So electrons travelling one way through the crystal have mostly one spin, and those travelling another way mostly the other, something once thought to need a ferromagnet. The spin alternates with direction: hence the name. In 2024, experiments on manganese telluride and chromium antimonide measured this splitting. Spin-sorted currents with no net magnetism, plus very fast magnetic dynamics, are why the team sees altermagnets as candidates for future spintronics: still a prospect, not a product. - 2019: concept proposed at Mainz - 2022: symmetry classification, hundreds of candidates - 2024: measured in MnTe and CrSb; named a Science breakthrough - 2026: Europhysics Prize - ferromagnet: net magnetism, spin-split electrons - antiferromagnet: no net magnetism, no spin splitting - altermagnet: no net magnetism, spin-split electrons - ferromagnet: mostly “up”, whichever way they move - antiferromagnet: no preference - altermagnet: “up” along one axis, “down” along the other ![Teams used photoemission: light knocks electrons out and their energies and directions are recorded. AI-generated still.](https://assets.planetpast.com/a/58/58eaf9806bc3b5e4.jpg) - **MnTe**: Nature, February - **CrSb**: Nature Communications, March Chapter VI · A third kind #### Altermagnetism Mainz University (2024 release): researchers at Mainz proposed the concept in 2019; Mainz University (2026 release): in 2022 the team published a complete symmetry classification and identified hundreds of candidate materials. Altermagnets have no net magnetisation, like antiferromagnets, yet show electronic properties once thought exclusive to ferromagnets, including highly spin-polarised currents together with ultrafast magnetic dynamics, which is why they are described as attractive candidates for next-generation spintronic devices; the spin polarisation alternates with direction, which gives the name. In February 2024 Krempaský and colleagues reported in Nature photoemission measurements of the predicted spin splitting in MnTe (manganese telluride); in March 2024 a Nature Communications paper reported a splitting of about 0.6 eV in CrSb (chromium antimonide) thin films. Science listed the discovery among the physics breakthroughs of 2024. Mainz and ScienceDaily describe possible uses in spintronics and information technology with words such as “could” and “potentially”: these are research prospects, not existing products. In the model, red and blue dots are electrons with opposite spins; the “different angles” are drawn as atoms stretched along two diagonals. Real altermagnet crystals are more complex. The 3D atoms, arrows, field lines and filings are simplified teaching models, not to scale. Sources: [Johannes Gutenberg University Mainz: 2026 Europhysics Prize honors discovery of a third fundamental class of magnetism](https://press.uni-mainz.de/2026-europhysics-prize-honors-discovery-of-a-third-fundamental-class-of-magnetism/); [Mainz University: Science lists the discovery of altermagnetism as a breakthrough in physics in 2024](https://press.uni-mainz.de/science-lists-the-discovery-of-altermagnetism-as-scientific-breakthrough-in-physics-in-2024/); [Krempaský et al., “Altermagnetic lifting of Kramers spin degeneracy”, Nature 626, 517–522 (2024), MnTe](https://research.jku.at/en/publications/altermagnetic-lifting-of-kramers-spin-degeneracy/); [“Direct observation of altermagnetic band splitting in CrSb thin films”, Nature Communications (2024)](https://doaj.org/article/04d92b44b4e047f3a97eb53ef1d8eaab); [ScienceDaily (18 Oct 2026), from Mainz University: the Europhysics Prize for altermagnetism](https://www.sciencedaily.com/releases/2026/10/261017230035.htm) ## Epilogue ### The crowd of tiny magnets *Epilogue* One small thing behind it all. So a magnet is a crowd of electrons that agree. Alternate them and the magnetism hides; alternate them in a crystal where the two sets sit at different angles, and the electrons still feel their spin. From a stone that found north and south to devices still being imagined, it all comes down to the electron's spin. - 1088: magnetised needle, China - 1600: Gilbert: the Earth is a magnet - 1820: Ørsted: currents make magnetism - 1970: Nobel Prize for antiferromagnetism - 1988: giant magnetoresistance - 2024: altermagnets measured ![All stills and illustrations in this film are AI-generated.](https://assets.planetpast.com/a/81/81c8b8638ab46d6d.jpg) - ferro: all together - antiferro: alternate, hidden - alter: alternate, still spin-split Epilogue · Sources #### How magnets work Field lines, electromagnetism, electron spin, ferromagnetism, domains, the Curie temperature and antiferromagnetism are established physics found in textbooks and the sources below. Altermagnetism is recent: predicted from 2019, classified in 2022 and measured in 2024 in published, peer-reviewed experiments; its possible applications are still research prospects. The 3D atoms, arrows, field lines and filings are simplified teaching models, not to scale. All stills are AI-generated. Sources: [Johannes Gutenberg University Mainz: 2026 Europhysics Prize honors discovery of a third fundamental class of magnetism](https://press.uni-mainz.de/2026-europhysics-prize-honors-discovery-of-a-third-fundamental-class-of-magnetism/); [ScienceDaily (18 Oct 2026), from Mainz University: the Europhysics Prize for altermagnetism](https://www.sciencedaily.com/releases/2026/10/261017230035.htm); [Mainz University: Science lists the discovery of altermagnetism as a breakthrough in physics in 2024](https://press.uni-mainz.de/science-lists-the-discovery-of-altermagnetism-as-scientific-breakthrough-in-physics-in-2024/); [Krempaský et al., “Altermagnetic lifting of Kramers spin degeneracy”, Nature 626, 517–522 (2024), MnTe](https://research.jku.at/en/publications/altermagnetic-lifting-of-kramers-spin-degeneracy/); [“Direct observation of altermagnetic band splitting in CrSb thin films”, Nature Communications (2024)](https://doaj.org/article/04d92b44b4e047f3a97eb53ef1d8eaab); [Wikipedia: Lodestone](https://en.wikipedia.org/wiki/Lodestone); [Wikipedia: History of the compass](https://en.wikipedia.org/wiki/History_of_the_compass); [NASA Goddard (D. P. Stern): William Gilbert and De Magnete](https://pwg.gsfc.nasa.gov/earthmag/DMGRev2.htm); [NASA Goddard: the core (main) magnetic field of the Earth](https://core2.gsfc.nasa.gov/terr_mag/core.html); [NCERT Physics, Class 12, chapter 5: Magnetism and Matter (PDF)](https://blog.mtg.in/wp-content/uploads/2023/05/leph105.pdf); [APS News: July 1820, Oersted and electromagnetism](https://aps.org/apsnews/2008/07/1820-oersted-electromagnetism); [Wikipedia: Electromagnet (Sturgeon 1824, Henry)](https://en.wikipedia.org/wiki/Electromagnet); [LibreTexts Chemistry: magnetic properties of materials](https://chem.libretexts.org/Courses/Saint_Marys_College_Notre_Dame_IN/CHEM_431%3A_Inorganic_Chemistry_%28Haas%29/CHEM_431_Readings/14%3A_Magnetism/14.02%3A_Magnetic_Properties_of_Materials); [HyperPhysics (Georgia State University): ferromagnetism](https://www.hyperphysics.gsu.edu/hbase/solids/ferro.html); [Wikipedia: Curie temperature](https://en.wikipedia.org/wiki/Curie_temperature); [NobelPrize.org: the Nobel Prize in Physics 1970](https://www.nobelprize.org/prizes/physics/1970/summary/); [Wikipedia: Electric motor](https://en.wikipedia.org/wiki/Electric_motor); [Wikipedia: Neodymium magnet](https://en.wikipedia.org/wiki/Neodymium_magnet); [Wikipedia: Magnetic resonance imaging](https://en.wikipedia.org/wiki/Magnetic_resonance_imaging); [National MagLab: how MRI works (interactive tutorial)](https://nationalmaglab.org/magnet-academy/watch-play/interactive-tutorials/magnetic-resonance-imaging-mri/); [UK REF impact case study: magnetic tunnel junction read heads (GMR used 1997–2005, then TMR)](https://impact.ref.ac.uk/CaseStudies/CaseStudy.aspx?Id=42270); [NobelPrize.org: press release, the Nobel Prize in Physics 2007](https://www.nobelprize.org/prizes/physics/2007/press-release/)