A team of researchers at the U.S. Department of Energy's (DOE) Argonne National Laboratory has identified a nickel oxide compound as an unconventional but promising candidate material for high-temperature superconductivity.
The team successfully synthesized single crystals of a metallic trilayer nickelate compound, a feat the researchers believe to be a first.
Materials scientists at Argonne National Laboratory synthesized these single crystals of a metallic trilayer nickelate compound via a high-pressure crystal growth process. A team led by John Mitchell, an Argonne Distinguished Fellow and associate director of the laboratory's Materials Science Division, describe the compound's potential as a high-temperature superconductor in the June 12 issue of Nature Physics.
Credit: Argonne National Laboratory
"It's poised for superconductivity in a way not found in other nickel oxides. We're very hopeful that all we have to do now is find the right electron concentration."
This nickel oxide compound does not superconduct, said John Mitchell, an Argonne Distinguished Fellow and associate director of the laboratory's Materials Science Division, who led the project, which combined crystal growth, X-ray spectroscopy, and computational theory. But, he added, "It's poised for superconductivity in a way not found in other nickel oxides. We're very hopeful that all we have to do now is find the right electron concentration."
Mitchell and seven co-authors announced their results in this week's issue of Nature Physics.
Superconducting materials are technologically important because electricity flows through them without resistance. High-temperature superconductors could lead to faster, more efficient electronic devices, grids that can transmit power without energy loss and ultra-fast levitating trains that ride frictionless magnets instead of rails.
Only low-temperature superconductivity seemed possible before 1986, but materials that superconduct at low temperatures are impractical because they must first be cooled to hundreds of degrees below zero. In 1986, however, discovery of high-temperature superconductivity in copper oxide compounds called cuprates engendered new technological potential for the phenomenon.
But after three decades of ensuing research, exactly how cuprate superconductivity works remains a defining problem in the field. One approach to solving this problem has been to study compounds that have similar crystal, magnetic and electronic structures to the cuprates.
Nickel-based oxides - nickelates - have long been considered as potential cuprate analogs because the element sits immediately adjacent to copper in the periodic table. Thus far, Mitchell noted, "That's been an unsuccessful quest." As he and his co-authors noted in their Nature Physics paper, "None of these analogs have been superconducting, and few are even metallic."
The nickelate that the Argonne team has created is a quasi-two-dimensional trilayer compound, meaning that it consists of three layers of nickel oxide that are separated by spacer layers of praseodymium oxide.
"Thus it looks more two-dimensional than three-dimensional, structurally and electronically," Mitchell said.
This nickelate and a compound containing lanthanum rather than praseodymium both share the quasi-two-dimensional trilayer structure. But the lanthanum analog is non-metallic and adopts a so-called "charge-stripe" phase, an electronic property that makes the material an insulator, the opposite of a superconductor.
"For some yet-unknown reason, the praseodymium system does not form these stripes," Mitchell said. "It remains metallic and so is certainly the more likely candidate for superconductivity."
Argonne is one of a few laboratories in the world where the compound could be created. The Materials Science Division's high-pressure optical-image floating zone furnace has special capabilities. It can attain pressures of 150 atmospheres (equivalent to the crushing pressures found at oceanic depths of nearly 5,000 feet) and temperatures of approximately 2,000 degrees Celsius (more than 3,600 degrees Fahrenheit), conditions needed to grow the crystals.
"We didn't know for sure we could make these materials," said Argonne postdoctoral researcher Junjie Zhang, the first author on the study. But indeed, they managed to grow the crystals measuring a few millimeters in diameter (a small fraction of an inch).
The research team verified that the electronic structure of the nickelate resembles that of cuprate
materials by taking X-ray absorption spectroscopy measurements at the Advanced Photon Source, a DOE Office of Science User Facility, and by performing density functional theory calculations. Materials scientists use density functional theory to investigate the electronic properties of condensed matter systems.
"I've spent my entire career not making high-temperature superconductors," Mitchell joked. But that could change in the next phase of his team's research: attempting to induce superconductivity in their nickelate material using a chemical process called electron doping, in which impurities are deliberately added to a material to influence its properties.
For the original study published in Nature Physics, see "Large orbital polarization in a metallic square-planar nickelate." Other Argonne authors included Materials Science Division scientists Antia Botana, Daniel Phelan, Hong Zheng, Michael Norman, and John Freeland of the Advanced Photon Source; the other author was Victor Pardo of the University of Santiago de Compostela in Spain.
Funding was provided by the U.S. Department of Energy, Office of Science and the National Science Foundation.
Argonne National Laboratory seeks solutions to pressing national problems in science and technology. The nation's first national laboratory, Argonne conducts leading-edge basic and applied scientific research in virtually every scientific discipline. Argonne researchers work closely with researchers from hundreds of companies, universities, and federal, state and municipal agencies to help them solve their specific problems, advance America's scientific leadership and prepare the nation for a better future. With employees from more than 60 nations, Argonne is managed by UChicago Argonne, LLC for the U.S. Department of Energy's Office of Science.
The U.S. Department of Energy's Office of Science is the single largest supporter of basic research in the physical sciences in the United States and is working to address some of the most pressing challenges of our time. For more information, visit the Office of Science website.
Jared Sagoff | EurekAlert!
Osaka university researchers make the slipperiest surfaces adhesive
18.10.2017 | Osaka University
Think laterally to sidestep production problems
17.10.2017 | King Abdullah University of Science & Technology (KAUST)
University of Maryland researchers contribute to historic detection of gravitational waves and light created by event
On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...
Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.
Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....
Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).
When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...
Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.
How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...
Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.
It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...
17.10.2017 | Event News
10.10.2017 | Event News
10.10.2017 | Event News
18.10.2017 | Materials Sciences
18.10.2017 | Physics and Astronomy
18.10.2017 | Physics and Astronomy