Polymerization in Magnetic Metamaterials


Researchers from Uppsala University have with the help of advanced computer simulations discovered that artificially produced magnetic materials, so called metamaterials, can give rise to the formation of polymers in a similar way to how atoms can couple together to form the building blocks of different types of plastics.

A large collection of rings, inside of which the magnetization gives rise to bonding between the rings. Networks of bonded rings can be regarded as artificial polymers and show similar behavior upon heating and cooling. Image: Samuel Dingeman Slöetjes.

A magnetic metamaterial is a material consisting of a large number of small magnets (typically are a hundred times smaller than a human hair), usually with an oblong or round shape. In a new study, the researchers have focused on metamaterials that instead are made of magnetic rings. These magnetic rings are more flexible than the classic nanomagnets, which gives more possibilities in how they can organise themselves and couple to each other.

“Something as simple as changing the shape of the nanoscale magnets gives rise to a set of completely new phenomena. These systems have more freedom to form interesting patterns, which could come in handy for example for use in potential neural networks, which is a type of computation based on how the brain performs operations,” says Samuel Dingeman Slöetjes, researcher at the Department of Physics and main author of the article.

The researchers also found that, when the temperature is increased, these polymers tend to become larger, up to a certain critical temperature, after which the polymers shrink again. This behavior, that the material’s state and its properties change with temperature, signifies a phase transition in the same way as when water changes to steam, or a piece of iron is heated to a critical temperature and then loses its magnetism.

The ring based metamaterial in the study is also interesting from the perspective of devices, since it could be used for fundamentally new computing technologies. Recently, magnetic metamaterials have gained interest for their ability to perform calculations in a way that imitates how the brain performs calculations, and is therefore more energy efficient for certain applications such as AI and machine learning.

“The ring-based metamaterial that we studied shows signs of network formation, similar to networks in the brain. Additionally, we have seen signs of ‘criticality’, a state that holds the middle between order and chaos, which has been speculated to be the state that the brain is in when it has optimized thinking processes. These similarities make it a promising avenue for further research,” says Matías Grassi, post doc at the Department of Physics and Astronomy and co-author of the study.

Article Reference

Samuel D. Slöetjes, Matías P. Grassi, and Vassilios Kapaklis, Polymerization in magnetic metamaterials, Phys. Rev. Research 5, L032029 – Published August 30, 2023. DOI:https://journals.aps.org/prresearch/abstract/10.1103/PhysRevResearch.5.L032029

The article has also been selected as a Letter by Physical Review Research, and can be found on the front page of the online version of the journal: https://journals.aps.org/prresearch/

Camilla Thulin

Last modified: 2023-08-04