Scientists have successfully employed light to observe magnetic domains and controlled these regions with an electric field in a special quantum antiferromagnet. This innovative approach facilitates real-time monitoring of magnetic behaviors, which could lead to advancements in next-gen electronics and memory devices, as well as a better grasp of quantum materials.
When we are captivated by a magnet, we tend to investigate further. When magnets attract physicists, they examine them at the quantum level.
Researchers from Osaka Metropolitan University and the University of Tokyo have effectively utilized light to visualize small magnetic regions, referred to as magnetic domains, in a unique quantum substance. Additionally, they have successfully manipulated these regions using an electric field, providing fresh insights into the intricate behavior of magnetic materials on a quantum scale, paving the path for future technological advancements.
Most people understand magnets that adhere to metal items. But what about those that don’t? Antiferromagnets fall into this category and have become a key focus for tech innovators globally.
Antiferromagnets are materials where the magnetic forces, or spins, are oriented in opposite directions, neutralizing one another and resulting in no overall magnetic field. As a result, these materials do not exhibit distinct north and south poles and do not behave like classic ferromagnets.
Particularly those with quasi-one-dimensional quantum attributes, meaning their magnetic properties are mainly restricted to one-dimensional chains of atoms, are seen as promising candidates for next-gen electronics and memory devices. However, the unique nature of antiferromagnetic materials is not only due to their non-attraction to metallic surfaces; studying these intriguing yet complex materials poses considerable challenges.
“It has been challenging to observe magnetic domains in quasi-one-dimensional quantum antiferromagnetic materials due to their low magnetic transition temperatures and minimal magnetic moments,” explained Kenta Kimura, an associate professor at Osaka Metropolitan University and the lead author of the research.
Magnetic domains are tiny areas within magnetic substances where the spins of atoms align similarly. The borders between these domains are known as domain walls.
Due to the ineffectiveness of traditional observation methods, the research team explored the quasi-one-dimensional quantum antiferromagnet BaCu2Si2O7. They used a phenomenon called nonreciprocal directional dichroism, where the light absorption of a material changes when the direction of light or its magnetic moments is reversed. This enabled them to visualize magnetic domains in BaCu2Si2O7, demonstrating that opposite domains exist within a single crystal, and that their domain walls primarily aligned with certain atomic chains, or spin chains.
“Seeing is believing, and understanding begins with direct observation,” Kimura said. “I’m excited that we could visualize the magnetic domains of these quantum antiferromagnets using a standard optical microscope.”
The research team also showed that these domain walls can be relocated using an electric field, thanks to a phenomenon known as magnetoelectric coupling, whereby magnetic and electric characteristics are linked. Even during movement, the domain walls preserved their initial orientation.
“This optical microscopy technique is simple and rapid, potentially allowing real-time observation of moving domain walls in the future,” Kimura stated.
This research represents a major advancement in understanding and controlling quantum materials, unlocking new opportunities for technological applications and venturing into new areas of physics that could lead to future quantum devices and materials.
“Utilizing this observation method across various quasi-one-dimensional quantum antiferromagnets could yield new understandings of how quantum fluctuations influence the development and movement of magnetic domains, assisting in the design of future electronics that incorporate antiferromagnetic materials,” added Kimura.
