With inspiration from bacteria and butterflies, researchers at Stockholm University have developed a new method that shows how nanomaterials can be produced in the future. In an article in the prestigious journal Proceedings of the National Academy of Sciences, Professor Lennart Bergström shows how a glass bottle and a simple hobby magnet can be used to produce and arrange extremely small cubes of iron oxide in a perfectly checkered pattern.

The new method can give magnetic films with superior information storage capacity," says Lennart Bergström.

To produce nanoparticles with a defined form and size and at the same time organize them in well-ordered structures is one of the few realistic ways of producing tomorrow’s nanomaterials on an industrial scale. It sounds like a dream, but the fact is that nature uses these construction principles in order to make the wings of a butterfly shimmer in all the colors of the rainbow and to create a compass needle of magnetic nanoparticles in certain bacteria.

In the article, Lennart Bergström and his colleagues show how it is possible to create a self-organizing system in which the system itself can achieve a flawless structure. Instead of slowly building up these intricate structures by for example etching, the particles are “programmed" to build the desired structure themselves. Nanoparticles are ideal building blocks for creating two- and three-dimensional structures with tailor-made properties. It is possible to combine metals, semiconductors, and magnetic nanoparticles in one and the same material, thereby obtaining entirely new combinations of properties.

“Our vision is to get nanoparticles to collaborate and construct complicated structures at will," says Lennart Bergström. “New types of nanostructured materials with unique characteristics, such as magnetic and catalytic properties, can then be created where they are most needed and in such a way that they can be readily reused. This opens up exciting possibilities to tailor the structure and function of materials, a goal for all materials chemists."

Name of article: “Magnetic field induced assembly of oriented superlattices from maghemite nanocubes"A. Ahniyaz, Y. Sakamoto, and L. Bergström, PNAS