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Scientists have taken a step towards creating powerful devices that use magnetic charge, creating the first ever three-dimensional copy of the material known as spin-ice.

Spin ice materials are extremely unusual because they have so-called defects that behave like the single pole of a magnet.

These unipolar magnets, also known as magnetic monopoles, do not exist in nature; when each magnetic material is cut in two, a new magnet with a north and south pole is always created.

For decades, scientists have searched everywhere for evidence of the existence of natural magnetic monopoles, hoping to finally group the fundamental forces of nature into a so-called theory of everything, putting all of physics under one roof.

However, in recent years, physicists have managed to create artificial versions of the magnetic monopole by creating two-dimensional materials from spin ice.

To date, these structures have successfully demonstrated a magnetic monopole, but it is impossible to obtain the same physics when the material is confined to a single plane. Indeed, it is the special three-dimensional geometry of the spin ice lattice that is the key to its unusual ability to create tiny structures that mimic magnetic monopoles.

In a new study, a team of scientists from Cardiff University created the first ever 3D copy of spin ice material using a sophisticated type of 3D printing and processing.

Scientists say 3D printing technology has allowed them to adapt the geometry of artificial spin ice, meaning they can control the way magnetic monopoles form and move in systems.

The ability to manipulate mini-monopole magnets in 3D could open up a range of applications that they say could be applied in areas from advanced computer storage to creating three-dimensional computing networks that mimic the neural structure of the human brain.

"For more than 10 years, scientists have been creating and studying artificial spin ice in two dimensions. By extending such systems to three dimensions, we get a much more accurate view of the spin monopole physics and can study the influence of surfaces,” said lead author Dr Sam Ladak from Cardiff University's School of Physics and Astronomy.

"This is the first time anyone has been able to create an exact three-dimensional replica of spin ice, intentionally, at the nanoscale."

The artificial spin ice was created using the latest three-dimensional nanowire technology, in which tiny nanowires were stacked in four layers in a lattice structure that was generally smaller than the width of a human hair.

Then, a special type of microscopy known as magnetic force microscopy, which is sensitive to magnetism, was used to visualize the magnetic charges present on the device, allowing the scientists to track the movement of single-pole magnets over a three-dimensional structure.

"Our work is important because it shows that nanoscale 3D printing technologies can be used to simulate materials that are normally synthesized using chemistry," the researchers say.

Ultimately, this work could provide the means to produce new magnetic metamaterials, in which the properties of the material are adjusted by controlling the three-dimensional geometry of the artificial lattice.

Magnetic storage devices, such as a hard drive or random-access magnetic memory devices – are another area that this breakthrough could seriously affect. Since modern devices use only two of the three available dimensions, this limits the amount of information that can be stored.

Since monopoles can move through a three-dimensional grid using a magnetic field, it is possible to create a real three-dimensional storage device based on a magnetic charge.

The work was published in Nature Communications.

 

ab-news.ru