The world’s thinnest magnet — just one atom thick — was created by scientists and could lead to huge advances in computer science and quantum physics.
This design is the brainchild of experts at the Lawrence Berkeley National Laboratory and neighboring University of California, Berkeley.
Made using a technique that the team says will be easily scalable, it has a single atomic layer of zinc oxide, dotted within which there are occasional cobalt atoms.
It uses a different underlying mechanism than other attempts to create 2D magnets, with the free electrons in the zinc oxide preserving the cobalt’s magnetism.
The magnet’s thickness is about a millionth that of a sheet of paper – and it’s also flexible and can operate at ambient temperatures, unlike many of its ilk.
As a result, the design could find application in so-called spintronic data storage, where information is encoded using the spin of an electron instead of charge.
The world’s thinnest magnet — just one atom thick — was created by scientists and could lead to huge advances in computer science and quantum physics. Pictured: The magnet is made by boiling a solution of cobalt, graphene oxide and zinc – sandwiching layers of cobalt-containing zinc oxide between layers of graphene, as shown
MAKING THE MAGNET
The thinnest magnet in the world consists of a single atomic layer of zinc oxide that occasionally contains a cobalt atom.
It was produced by baking a solution of cobalt, graphene oxide and zinc for a few hours in a conventional laboratory oven.
This yielded sheets of zinc oxide (with cobalt), sandwiched between layers of graphene.
Finally, the graphene is burned off to expose the single-layer magnet.
“There are no major obstacles for the industry to adopt our solution-focused method,” noted Professor Yao.
“It is potentially scalable for mass production at a lower cost.”
The team confirmed that the magnet was only one layer of atoms thick by analyzing it with both scanning and transmission electron microscopy.
And they used X-ray analysis to prove that the material was indeed magnetic, not only under ambient conditions, but at temperatures as high as 212°F (100°C).
The team found that the system becomes weakly magnetic at a concentration of cobalt atoms of about 5-6 percent — but a very strong magnet forms at about 12 percent.
But when the cobalt concentration rose above 15 percent, the team was surprised to find that the magnet shifts into an exotic quantum state of “frustration,” in which different magnetic domains in the system work against each other.
“Our 2D magnet system shows a clear mechanism compared to previous 2D magnets,” added Mr. Chen.
‘We think this unique mechanism is due to the free electrons in zinc oxide.’
The study was conducted by materials scientist Jie Yao of the Lawrence Berkeley National Laboratory and colleagues.
“We are the first to create a room temperature 2D magnet that is chemically stable under ambient conditions,” says Professor Yao.
His colleague Rui Chen added that the discovery was also exciting because it “reveals a new mechanism to realize 2D magnetic materials.”
Memory devices today often use relatively thin magnetic films — but on an atomic scale, these are still three-dimensional, with thicknesses on the order of hundreds to thousands of atoms.
Thinner and smaller magnets approaching two-dimensionality are attractive to researchers because they have the potential to store data at much higher densities — meaning less space would be needed to hold a given volume of information.
While explorations of two-dimensional magnetic materials have shown promise so far, such magnets tend to operate in certain conditions and become chemically unstable and non-functional at near room temperature.
‘State-of-the-art 2D magnets need very low temperatures to function, but for practical reasons a data center has to operate at room temperature,’ explains Professor Yao.
“Theoretically, we know that the smaller the magnet, the greater the potential data density of the disk,” he added.
“Our 2D magnet is not only the first to work at room temperature or higher, but it is also the first magnet to reach the true 2D limit — it’s as thin as a single atom!”
According to the team, their new magnet design will also pave the way for new ways to study quantum physics.
“Our atomically thin magnet provides an optimal platform to explore the quantum world,” said Professor Yao.
“It opens up every single atom for research, which could reveal how quantum physics controls each individual magnetic atom and the interactions between them.”
‘With a conventional bulk magnet where most of the magnetic atoms are buried deep in the material, it would be quite a challenge to do such studies.’
According to Mr. Chen, the mechanism underlying the magnetism in their material – which they call a “cobalt-doped van der Waals zinc oxide magnet” – differs from that of previous attempts to create a 2D magnet.
The difference, he says, lies in the way in which free electrons from the (non-magnetic) zinc oxide can act as an intermediary and ensure that the cobalt atoms in the atomic layer point in the right direction – keeping them magnetic.
‘Free electrons are components of electric currents. They move in the same direction to conduct electricity’, explains Professor Yao, who compares the movement of electrons in metals or semiconductors to the flow of molecules in a stream of water.
The thinnest magnet in the world consists of a single atomic layer of zinc oxide that occasionally contains a cobalt atom. It was produced by baking a solution of cobalt, graphene oxide and zinc for a few hours in a conventional laboratory oven. This produced sheets of zinc oxide (shown in yellow and blue, with cobalt in red) sandwiched between layers of graphene. Finally, the graphene is burned off to expose the single-layer magnet
“I believe the discovery of this new, robust, truly two-dimensional magnet at room temperature is a real breakthrough,” said author and physicist Robert Birgeneau of the University of California, Berkeley.
“In addition to its obvious significance for spintronic devices, this 2D magnet is fascinating at the atomic level and reveals for the first time how cobalt magnetic atoms interact at ‘long’ distances” through a complex two-dimensional network..’
“Our results are even better than we expected, which is very exciting. In science, experiments can usually be very challenging. But when you finally realize something new, it’s always very satisfying’, he concluded.
The study’s full findings were published in the journal nature communication.
WHAT IS A MAGNETIC FIELD AND HOW IS IT MADE?
A magnet is any object that has a magnetic field. It attracts ferrous objects such as pieces of iron, steel, nickel and cobalt.
Today, magnets are artificially made in various shapes and sizes depending on their use.
One of the most common magnets – the bar magnet – is a long, rectangular rod of uniform cross-section that attracts pieces of ferrous objects
A magnetic field is the space around a magnet, in which magnetic force is exerted.
If a bar magnet is placed in such a field, it will experience magnetic forces.
However, the field remains even if the magnet is removed. The direction of the magnetic field at a point is the direction of the resultant force acting on a hypothetical north pole placed at that point.
When current flows in a wire, a magnetic field is created around the wire.
From this it is deduced that magnetic fields are produced by the movement of electric charges. A magnetic field of a bar magnet is thus created by the movement of negatively charged electrons in the magnet.