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The tiniest magnet in the world - one-atom thick

A magnet with a thickness of one atom in a two-dimensional structure developed by scientists from the University of Berkeley could advance the development of new applications in the fields of computing and electronics

[Translation by Dr. Moshe Nachmani]

Illustration of the innovative magnet: red - cobalt; blue – oxygen; Yellow – Zinc [Courtesy of Berkeley Lab]
Illustration of the innovative magnet: red - cobalt; blue – oxygen; Yellow – Zinc [Courtesy of Berkeley Lab]

The development of an ultrathin magnet that operates at room temperature could lead to the development of new applications in the fields of computing and electronics - such as high-density and compact spintronic memory devices - and new tools for the study of quantum physics. The extremely thin magnet, which was recently reported in the prestigious scientific journal Nature Communications., will be able to significantly advance the fields of next-generation memory devices, computing, spintronics (the term in Wikipedia) and quantum physics. The magnet was developed by scientists from the Lawrence Berkeley National Laboratory at the US Department of Energy and the University of Berkeley.

"We are the first ever to develop a two-dimensional magnet that works at room temperature and is chemically stable under mild conditions," said the paper's lead author Jie Yao, a professor of materials science and engineering at the University of Berkeley. "This discovery is particularly exciting because it not only demonstrates that two-dimensional magnetism is chemically possible at room temperature, but it also reveals a new mechanism for creating two-dimensional magnetic materials," added one of the researchers.

The magnetic components of existing memory devices are usually made of thin layers of magnetic material. However, at the atomic level, these materials are still three-dimensional, that is, hundreds or thousands of atoms thick. For decades, researchers have been trying to find ways to produce thinner and smaller two-dimensional magnets that could allow information to be stored at a higher level of compression. Previous achievements in the field of two-dimensional magnetic materials have indeed shown promising results. However, these first two-dimensional magnets lose their magnetism and become chemically unstable at room temperature. "Advanced two-dimensional magnets need extremely low temperatures in order for them to function properly. However, for practical reasons, an information center is required to operate at room temperature," explains the lead researcher. "Our two-dimensional magnet is not only the first to operate at or above room temperature, but it is the first magnet ever to reach the true two-dimensional limit - it is the thickness of a single atom!", marvels at the achievement of the lead researcher. 

The researchers explain that their discovery could also provide new opportunities in the field of quantum physics. "Our discovery opens a window for the study of every single atom in this new field of ours, and may reveal how quantum physics controls each and every one of the atomic magnets and better explain the interrelationships between them," adds the lead researcher.

The researchers synthesized the new two-dimensional magnet - known as cobalt-doped van der Waals zinc-oxide magnet, from a solution of graphene oxide, zinc and cobalt. Only a few hours of "cooking" the mixture in a normal laboratory oven led to the creation of an atomic monolayer of zinc oxide combined with cobalt atoms integrated within layers of graphene. In a final step, the graphene is removed by burning it, leaving a monoatomic layer of zinc oxide doped with cobalt atoms.      

Illustration of the innovative magnet: red - cobalt; blue – oxygen; Yellow – Zinc [Courtesy of Berkeley Lab]

"Thanks to our material, there are no longer any significant limitations for industry in adopting our solution-based method," said the lead researcher. "Our method can also be properly adapted for mass production at lower costs."

In order to prove that the thickness of the new magnet is indeed monoatomic, the researchers conducted measurements using separate spectroscopic methods (SEM, TEM) and proved that this is indeed its morphology. In addition, the researchers also measured the spatial structure of the material using X-ray experiments. The researchers found that the graphene-zinc-oxide system becomes slightly magnetic when 6-5 percent of cobalt atoms are added. Increasing the concentration of cobalt atoms to a level of 12 percent leads to obtaining a strong magnet. Much to their surprise, an amount of cobalt at a concentration higher than 15 percent turned the two-dimensional magnet into a rare quantum state where different magnetic states are in competition with each other. And unlike previous two-dimensional magnets, which lost their magnetism at or above room temperature, the researchers found that their innovative material not only works properly at room temperature but even at 100 degrees Celsius. "Our two-dimensional magnet demonstrates a distinct mechanism compared to previous two-dimensional magnets," explains the lead researcher. "And we believe that this unique mechanism is caused by the free electrons found in the zinc oxide. Electrons that are free to move from place to place are an essential component of an electric current. They move in the same direction in order to conduct electricity," explains the lead researcher. The innovative material, which can be bent into almost any shape without breaking, and which is a million times thinner than a sheet of paper, could help in the development of applications in electronic components based on the spin property of the electrons (spintronics), an innovative technology based on the directionality of the electronic spin and not on the electric charge his in order to encode and store data. "Our two-dimensional magnet will enable the production of extremely tiny spintronics devices while utilizing the spin property of the electrons," says the lead researcher.   

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