A new kind of magnetism has been measured for the first time. Altermagnets, which contain a blend of properties from different classes of existing magnets, could be used to make high capacity and fast memory devices or new kinds of magnetic computers.
Until the 20th century, there was thought to be only one kind of permanent magnet, a ferromagnet, the effects of which can be seen in objects with relatively strong external magnetic fields like fridge magnets or compass needles.
These fields are caused by the magnetic spins of the magnets’ electrons lining up in one direction.
But, in the 1930s, French physicist Louis Néel discovered another kind of magnetism, called antiferromagnetism, where the electrons’ spins are alternately up and down. Although antiferromagnets lack the external fields of ferromagnets, they do show interesting internal magnetic properties because of the alternating spins.
Then in 2019, researchers predicted a perplexing electric current in the crystal structure of certain antiferromagnets, called the anomalous Hall effect, which couldn’t be explained by the conventional theory of alternating spins. The current was moving without any external magnetic field.
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