A group of scientists from the City College of New York reported that they noticed a strong magneto-optical response. The magnetic material literally absorbed light, reacting with it orders of magnitude stronger than previously known. The discovered property promises to lead to the creation of magnetic lasers and new data recording systems based not on the usual magnetoelectric interaction, but on magneto-optical interaction.
Trapped in a magnetic material is light. Artistic representation. Image Source: City College of New York
In their experiment, scientists studied the properties of magnetic van der Waals materials. Specifically, the layered semiconductor magnetic material CrSBr. Such materials, usually consisting of two-dimensional layers, have an internal magnetic structure due to the inclusion of magnetic elements and are capable of exhibiting interesting quantum properties. The pattern did not disappoint. When an external magnetic field was applied, it reacted so strongly to a light pulse in the near infrared region that this was reflected in a change in the color of the material.
But the structure of the material can react to light on its own. In the presented materials, exciton quasiparticles appear, which are associated both with the material and are capable of reacting to photons. Usually such interactions are very, very weak, but in the case of an experimental sample, the internal structure of the magnet, as it were, caught the incoming light pulse and showed a strong reaction to it.
As experiments have shown, the optical response of this material to magnetic phenomena is orders of magnitude stronger than in conventional magnets. “Because the light is reflected inside the magnet, the interaction between them is really enhanced,” said Dr. Florian Dirnberger, lead author of the study. “For example, when an external magnetic field is applied, the reflection of light in the near infrared region changes so much that the material practically changes its color. This is a fairly strong magneto-optical response.”
“Technological applications of magnetic materials today are mainly related to magnetoelectric phenomena. — Study co-author Jiamin Quan said. “Given such a strong interaction between magnetism and light, we can hope to create magnetic lasers and revisit the old concepts of optically controlled magnetic memory.”
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