Scientists from Osaka Metropolitan University and the University of Tokyo have discovered a new way to visualize tiny magnetic regions, called magnetic domains, in specialized quantum materials.
Using light, they were able to see these magnetic domains and even move them with an electric field.
Their findings, published in Physical Review Letters, offer valuable insights into the behavior of magnetic materials at the quantum level and could pave the way for future advancements in technology.
Most people are familiar with regular magnets that stick to metal surfaces, but not all magnets behave this way.
One such type is antiferromagnets, which have gained interest from researchers developing next-generation electronics.
In antiferromagnets, the magnetic forces, or spins, point in opposite directions, canceling each other out. As a result, they don’t have a north or south pole and don’t behave like traditional magnets.
These unique properties make antiferromagnets especially interesting for future technology.
One specific group, known as quasi-one-dimensional quantum antiferromagnets, is made up of magnetic characteristics confined to one-dimensional chains of atoms.
These materials could potentially be used in new types of memory devices and electronics, but they are difficult to study because of their small magnetic moments and low transition temperatures.
“Observing the magnetic domains in these materials has been a challenge,” said Kenta Kimura, lead author of the study and associate professor at Osaka Metropolitan University.
Magnetic domains are small regions where the spins of atoms align in the same direction, and the boundaries between these regions are called domain walls.
To overcome this challenge, the research team studied a quantum antiferromagnet called BaCu2Si2O7, using a technique called nonreciprocal directional dichroism. This method allowed them to visualize how the material absorbs light differently depending on the direction of light or its magnetic properties.
By using this technique, the team was able to see the magnetic domains within the material, showing that opposite domains could exist within a single crystal. These domains were aligned along specific atomic chains, called spin chains.
“I’m excited that we could actually visualize these magnetic domains with a simple optical microscope,” said Kimura. “Seeing is believing, and understanding starts with direct observation.”
In addition to visualizing the domains, the scientists were able to move the domain walls by applying an electric field. This is possible because of a phenomenon called magnetoelectric coupling, where the magnetic and electric properties of the material are interconnected. Even as they moved, the domain walls maintained their original direction.
This new method of visualizing magnetic domains is not only simple and fast but could also allow real-time observation of moving domain walls in the future. The findings are an important step in understanding how quantum materials behave, which could lead to the development of new technologies and quantum devices.
According to Kimura, this method could be applied to other quantum antiferromagnets, providing deeper insights into how quantum fluctuations influence magnetic domains and helping to design future electronics using these unique materials.
