Researchers at Aalto University have developed a type of metamaterial that was previously unattainable by current technologies, thanks to a novel strategy. Scientists are able to develop materials with desirable qualities for commercial uses by tailoring metamaterials and metasurfaces to have precise electromagnetic properties, unlike normal materials.
The magnetic properties of a material can affect how it interacts with light. Image Credit: Ihar Faniayeu/Aalto University
Benefiting from the Nonreciprocal Magneto Electric (NME) phenomenon is the novel metamaterial. The NME effect suggests a connection between the various field components of light or other electromagnetic waves and certain material properties, such as its polarization and magnetization.
Although the NME effect is minimal in natural materials, due to the possible technological benefits, scientists have been attempting to increase it through the use of metamaterials and metasurfaces.
So far, the NME effect has not led to realistic industrial applications. Most of the proposed approaches would only work for microwaves and not visible light, and they also could not be fabricated with available technology.
Shadi Safaei Jazi, Doctoral Researcher, Aalto University
The group developed an optical NME metamaterial that can be produced with current technology by combining nanofabrication methods and regular materials.
The new material enables applications such as creating truly one-way glass, which would otherwise require a strong external magnetic field to function. Presently available "one-way" glass is actually only partially transparent, allowing light to pass through in both directions.
It functions similarly to one-way glass when there is a difference in light between the two sides (such as inside and outside a window). However, since light could only pass through an NME-based one-way glass in one direction, it would not require a variation in brightness.
Just imagine having a window with that glass in your house, office, or car. Regardless of the brightness outside, people would not be able to see anything inside, while you would enjoy a perfect view from your window.
Shadi Safaei Jazi, Doctoral Researcher, Aalto University
By obstructing the thermal emissions that current solar cells radiate back toward the sun, which lowers the amount of energy they absorb, this one-way glass could also increase the efficiency of solar cells if technology advances.
Journal Reference:
Safaei Jazi, S., et.al. (2024) Optical Tellegen metamaterial with spontaneous magnetization. Nature Communications. doi.org/10.1038/s41467-024-45225-y.
Source: https://www.aalto.fi/en