Magnetic-like materials have an internal vortex that can only be driven by circularly polarized lasers.
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Researchers have taken control of previously elusive material behavior. looks like magnetismwhich in the future can be used to create more advanced hard drives.
If you place a bar magnet in a magnetic field, it will rotate under the influence of the field, but the material, which has a property called ferroaxiality, will remain stationary in any field known to physics. Now, Zhiyang Zeng from the Max Planck Institute for the Structure and Dynamics of Matter in Germany and his colleagues have figured out how to control ferroaxiality using a laser.
You can imagine ordinary magnetic materials consisting of many tiny bar magnets. Zeng says that for ferroaxial materials, it's more accurate to think of a collection of dipoles—two opposing electrical charges separated by a short distance—that swirl in tiny eddies. He and his colleagues realized that they could control these vortices using pulses of laser light, but only if that light also contained some vorticity.
They tuned their lasers to produce circularly polarized light that, when struck by a ferroaxial material—in this case, a compound of rubidium, iron, molybdenum, and oxygen—provided some rotation to the material's atoms. This changed the direction of movement of the dipoles.
Team Member Michael first from the Max Planck Institute for the Structure and Dynamics of Matter say the team has long known that light can be a powerful tool for manipulating materials, for example turning conductors into insulators and vice versa, but tuning its properties to manipulate a material has been a technical challenge.
“As a proof of principle, this is a great result,” says Ooooh here at Radboud University in the Netherlands. He says this adds material to the growing array of options for building more efficient and stable systems. memory devices – hard drives on which information is stored in the form of electromagnetic charges.
But the experiment currently requires cooling the material to about -70.°C (-94°F), and the team's laser was quite large, so more work will be needed before making practical devices is a realistic possibility, Furst says.
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