Main attraction: Scientists create world’s thinnest magnet


IMAGE: Illustration of magnetic coupling in a cobalt-doped zinc-oxide monolayer. Red, blue, and yellow spheres represent cobalt, oxygen, and zinc atoms, respectively.
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Credit: Berkeley Lab

The advancement of an ultrathin magnet that runs at space temperature level might result in brand-new applications in computing and electronic devices – such as high-density, compact spintronic memory gadgets – and brand-new tools for the research study of quantum physics.

The ultrathin magnet, which was just recently reported in the journal Nature Communications , might make huge advances in next-gen memories, computing, spintronics, and quantum physics. It was found by scientists at the Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) and UC Berkeley.

“We’re the first to make a room-temperature 2D magnet that is chemically stable under ambient conditions,” stated senior author Jie Yao, a professors researcher in Berkeley Lab’s Materials Sciences Division and associate teacher of products science and engineering at UC Berkeley.

“This discovery is amazing due to the fact that it not just makes 2D magnetism
possible at space temperature level, however it likewise discovers a brand-new system to understand 2D magnetic products,” added Rui Chen, a UC Berkeley graduate student in the Yao Research Group and lead author on the study.”

The magnetic element these days’s memory gadgets is generally made from magnetic thin movies. But at the atomic level, these magnetic movies are still three-dimensional – hundreds or countless atoms thick. For years, scientists have actually looked for methods to make thinner and smaller sized 2D magnets and therefore allow information to be kept at a much greater density.

Previous accomplishments in the field of 2D magnetic products have actually brought appealing outcomes. But these early 2D magnets lose their magnetism and end up being chemically unsteady at space temperature level.

“State-of-the-art 2D magnets need very low temperatures to function. But for practical reasons, a data center needs to run at room temperature,” Yao stated. “Theoretically, we know that the smaller the magnet, the larger the disc’s potential data density. Our 2D magnet is not only the first that operates 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!”

The scientists state that their discovery will likewise allow brand-new chances to study quantum physics. “Our atomically thin magnet offers an optimal platform for probing the quantum world,” Yao stated. “It opens up every single atom for examination, which may reveal how quantum physics governs each single magnetic atom and the interactions between them. With a conventional bulk magnet where most of the magnetic atoms are deeply buried inside the material, such studies would be quite challenging to do.”

The making of a 2D magnet that can take the heat


The scientists manufactured the brand-new 2D magnet – called a cobalt-doped van der Waals zinc-oxide magnet – from a service of graphene oxide, zinc, and cobalt. Just a couple of hours of baking in a standard laboratory oven changed the mix into a single atomic layer of zinc-oxide with a smattering of cobalt atoms sandwiched in between layers of graphene. In a last action, graphene is burned away, leaving simply a single atomic layer of cobalt-doped zinc-oxide.

“With our material, there are no major obstacles for industry to adopt our solution-based method,” stated Yao. “It’s potentially scalable for mass production at lower costs.”

To validate that the resulting 2D movie is simply one atom thick, Yao and his group carried out scanning electron microscopy experiments at Berkeley Lab’s Molecular Foundry to determine the product’s morphology, and transmission electron microscopy imaging to penetrate the product atom by atom.

With evidence in hand that their 2D product truly is simply an atom thick, the scientists went on to the next obstacle that had actually puzzled scientists for many years: Demonstrating a 2D magnet that effectively runs at space temperature level.

X-ray experiments at Berkeley Lab’s Advanced Light Source identified the 2D product’s magnetic criteria under heat. Additional X-ray experiments at SLAC National Accelerator Laboratory’s Stanford Synchrotron Radiation Lightsource validated the electronic and crystal structures of the manufactured 2D magnets. And at Argonne National Laboratory’s Center for Nanoscale Materials, the scientists imaged the 2D product’s crystal structure and chemical structure utilizing transmission electron microscopy.

As an entire, the research study group’s laboratory experiments revealed that the graphene-zinc-oxide system ends up being weakly magnetic with a 5-6% concentration of cobalt atoms. Increasing the concentration of cobalt atoms to about 12% leads to an extremely strong magnet.

To the scientists’ surprise, a concentration of cobalt atoms surpassing 15% moves the 2D magnet into an unique quantum state of “frustration,” where various magnetic states within the 2D system remain in competitors with each other.

And unlike previous 2D magnets, which lose their magnetism at space temperature level or above, the scientists discovered that the brand-new 2D magnet not just operates at space temperature level however likewise at 100 degrees Celsius (212 degrees Fahrenheit).

“Our 2D magnetic system shows a distinct mechanism compared to previous 2D magnets,” stated Chen. “And we think this unique mechanism is due to the free electrons in zinc oxide.”

True north: Free electrons keep magnetic atoms on track


When you command your computer system to conserve a file, that info is kept as a series of ones and nos in the computer system’s magnetic memory, such as the magnetic disk drive or a flash memory. And like all magnets, magnetic memory gadgets include tiny magnets with 2 poles – north and south, the orientations of which follow the instructions of an external electromagnetic field. Data is composed or encoded when these small magnets are turned to the preferred instructions.

According to Chen, zinc oxide’s totally free electrons might function as an intermediary that makes sure the magnetic cobalt atoms in the brand-new 2D gadget continue pointing in the very same instructions – and therefore remain magnetic – even when the host, in this case the semiconductor zinc oxide, is a nonmagnetic product.

“Free electrons are constituents of electric currents. They move in the same direction to conduct electricity,” Yao included, comparing the motion of totally free electrons in metals and semiconductors to the circulation of water particles in a stream of water.

The scientists state that brand-new product – which can be bent into nearly any shape without breaking, and is 1 millionth the density of a single sheet of paper – might assist advance the application of spin electronic devices or spintronics, a brand-new technology that utilizes the orientation of an electron’s spin instead of its charge to encode information. “Our 2D magnet may enable the formation of ultra-compact spintronic devices to engineer the spins of the electrons,” Chen stated.

“I believe that the discovery of this new, robust, truly two-dimensional magnet at room temperature is a genuine breakthrough by Jie Yao and his students,” stated co-author Robert Birgeneau, a professors senior researcher in Berkeley Lab’s Materials Sciences Division and teacher of physics at UC Berkeley who co-led the research study’s magnetic measurements. “In addition to its obvious significance to spintronic devices, this 2D magnet is fascinating at the atomic level, revealing for the first time how cobalt magnetic atoms interact over ‘long’ distances” through an intricate two-dimensional network, he included.

“Our results are even better than what we expected, which is really exciting. Most of the time in science, experiments can be very challenging,” he stated. “But when you finally realize something new, it’s always very fulfilling.”

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Co-authors on the paper consist of scientists from Berkeley Lab, consisting of Alpha N’Diaye and Padraic Shafer of the Advanced Light Source; UC Berkeley; UC Riverside; Argonne National Laboratory; and Nanjing University and the University of Electronic Science and Technology of China.

The Advanced Light Source and Molecular Foundry are DOE nationwide user centers at Berkeley Lab.

The Stanford Synchrotron Radiation Lightsource is a DOE nationwide user center at SLAC National Accelerator Laboratory.

The Center for Nanoscale Materials is a DOE nationwide user center at Argonne National Laboratory.

This work was moneyed by the DOE Office of Science, the Intel Corporation, and the Bakar Fellows Program at UC Berkeley.

Founded in 1931 on the belief that the most significant clinical obstacles are best resolved by groups, Lawrence Berkeley National Laboratory and its scientists have actually been acknowledged with 14 Nobel Prizes. Today, Berkeley Lab scientists establish sustainable energy and ecological options, create beneficial brand-new products, advance the frontiers of computing, and probe the secrets of life, matter, and deep space. Scientists from all over the world depend on the Lab’s centers for their own discovery science. Berkeley Lab is a multiprogram nationwide lab, handled by the University of California for the U.S. Department of Energy’s Office of Science.

DOE’s Office of Science is the single biggest advocate of fundamental research study in the physical sciences in the United States, and is working to attend to a few of the most important obstacles of our time. For more info, please see energy.gov/science.

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