Confirmation of the existence of a new form of magnetism

A new type of magnetism has been measured for the first time. Alternative magnets that combine the properties of different types of existing magnets could be used to make high-capacity, high-speed memory devices and new types of magnetic computers.

Until the 20th century, permanent magnets were thought to consist of only one type of ferromagnetic material. Ferromagnetic effects are seen in objects with relatively strong external magnetic fields, such as refrigerator magnets and compass needles.

These fields are caused by the magnetic spins of the magnet’s electrons aligned in one direction.

But in the 1930s, French physicist Louis Niel discovered another type of magnetism called antiferromagnetism, in which the spin of the electrons alternates up and down. Although antiferromagnets do not have the external magnetic field of ferromagnets, they exhibit interesting internal magnetic properties because of their alternating spins.

And in 2019, researchers Complex currents in the crystal structure of certain antiferromagnets, called the anomalous Hall effect, which could not be explained using the conventional alternating spin theory. Current flowed without an external magnetic field.

When we looked at the crystal from the perspective of a sheet of spins, it seemed to us that: A third type of permanent magnetism, called vicarious magnetism, may be responsible. Alternating magnets look like antiferromagnets, but the sheets of spin look the same no matter what angle they are rotated from. This explains the Hall effect, but no one had seen the electronic signature of the structure itself, so scientists weren’t sure if it was definitely a new kind of magnetism.

now, Juraj Krempaski and his colleagues at the Paul Scherrer Institute in Billigen, Switzerland, and his colleagues have discovered that by measuring the electronic structure within the crystals of magnesium telluride, previously thought to be antiferromagnetic, they were able to create an alternating magnet. confirmed the existence of

To do this, they measured how light reflected off magnesium telluride and found the energy and speed of the electrons in the crystal. After mapping these electrons, they found that they matched almost exactly the predictions given by simulations of alternating current magnetic materials.

The electrons appear to be split into two groups, which allows them to move more within the crystal and is the source of the unusual magnetic properties. “This gave us direct evidence that we can talk about metamorphic magnets and that they behave as predicted by theory,” Krempasky says.

This grouping of electrons appears to originate from the nonmagnetic tellurium atoms in the crystal structure, which separates the magnesium’s magnetic charge into each plane, allowing for its unusual rotational symmetry.

“It’s really amazing to prove that these substances actually exist,” he says. Richard Evans At York University, UK. Not only can electrons in alternating magnets move more freely than electrons in antiferromagnets, but this new type of magnet has no external magnetic fields like ferromagnets, so it could be used to create non-interfering magnetic devices. Evans says. each other.

This characteristic can increase the storage capacity of your computer’s hard drive. This is because commercially available devices are packed with ferromagnetic materials so tightly that external magnetic fields in the material begin to interfere. AC magnets can be packed more densely.

They say this magnet could even lead to spintronic computers that use magnetic spins instead of electrical current to perform measurements and calculations. joseph barker At the University of Leeds in the UK, memory and computer chips have been combined into a single device. “This may give more hope to the idea that spintronic devices can become a reality,” Barker says.