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Arthur T Knackerbracket has found the following story:

Materials scientists who work with nano-sized components have developed ways of working with their vanishingly small materials. But what if you could get your components to assemble themselves into different structures without actually handling them at all?

Verner Håkonsen works with cubes so tiny that nearly five billion of them could fit on a pinhead.

He cooks up the cubes in the NTNU NanoLab, in a weird-looking glass flask with three necks on the top using a mixture of chemicals and special soap.

And when he exposes these invisible cubes to a magnetic field, they perform a magical feat: they assemble themselves into whatever shape he wants.

"It's like building a house, except you don't have to build it," he says. The magnetic force along with other forces cause "the house to build itself—all the building blocks assemble themselves perfectly under the right conditions."

Although researchers have previously been able to cause nanoparticles to assemble themselves in different ways, Håkonsen and his colleagues are the first to show how important magnetism can be with respect to the mechanical properties of certain nanoparticle structures. The researchers called their tiny nanocube creations superstructures or supercrystals because the nanocubes are organized in an ordered pattern, kind of like atoms in a crystal. "Supercrystals are particularly interesting because they show enhanced properties compared with a single nanoparticle or with a bulk material," Håkonsen said.

The big finding is that when magnetic cubes are self-assembled in what the researchers call a supercrystal—in shapes like lines or rods or helices, for example—the cohesive energy between the particles in the supercrystal can increase by as much 45 percent because of the magnetic interactions between the cubes.

"That means the energy holding the whole thing together increases up to 45 percent," he said.

The strength of the supercrystals in combination with their enhanced magnetic properties will be key to developing future uses, which could span everything from applications for the automotive industry to information technology. Håkonsen's research has just been published in the journal Advanced Functional Materials.

Magnetically Enhanced Mechanical Stability and Super‐Size Effects in Self‐Assembled Superstructures of Nanocubes, Advanced Functional Materials (DOI: 10.1002/adfm.201904825)

Original Submission