Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Ames Laboratory scientists solve riddle of strangely behaving magnetic material

Materials scientists at the U.S. Department of Energy’s (DOE) Ames Laboratory have found an accurate way to explain the magnetic properties of a compound that has mystified the scientific community for decades.

The compound of lanthanum, cobalt and oxygen (LaCoO3) has been a puzzle for over 50 years, due to its strange behavior. While most materials tend to lose magnetism at higher temperatures, pure LaCoO3 is a non-magnetic semiconductor at low temperatures, but as the temperature is raised, it becomes magnetic. With the addition of strontium on the La sites the magnetic properties become even more prominent until, at 18 percent strontium, the compound becomes metallic and ferromagnetic, like iron.

“It’s just strange stuff. The material has attracted a lot of attention since about 1957, when people started picking it up and really studying it,” said Bruce Harmon, senior scientist at the Ames Laboratory. “Since then, there have been over 2000 pertinent papers published.”

Traditional theories to describe the compound’s behavior originated with physicist John B. Goodenough, who postulated that as temperature rises, the spin state of the d-electrons of cobalt changes, yielding a net magnetic moment.

“Back then it was more of a chemist’s atomic model of electron orbits that suggested what might be going on,” explained Harmon. “It’s a very local orbital picture and that theory has persisted to this day. It’s become more sophisticated, but almost all the theoretical descriptions are based on that model.”

But when Ames Laboratory research partners at the Argonne National Laboratory and the University of California, Santa Cruz performed X-ray absorption spectroscopy measurements of the material, the theory didn’t fit what they were observing.
”They knew that we could calculate x-ray absorption and magnetic dichroism, so we started doing that. It is a case where we fell into doing what we thought was a routine calculation, and it turned out we discovered a totally different explanation,” said Harmon. “We found we could explain pretty much everything in really nice detail, but without explicitly invoking that local model,” said Harmon.

The scientists found that a small rhombohedral distortion of the LaCoO3 lattice structure, which had largely been ignored, was key.

“We found that the total electronic energy of the lattice depends sensitively on that distortion,” explained Harmon. “If the distortion becomes smaller (the crystal moves closer to becoming cubic), the magnetic state of the crystal switches from non-magnetic to a state with 1.3 Bohr magnetons per Co atom.”

Ames Laboratory scientists Bruce Harmon and Yongbin Lee partnered with the researchers at the Argonne National Laboratory and the University of California, Santa Cruz to publish a paper in Physical Review Letters, “Evolution of Magnetic Oxygen States in Sr-Doped LaCO3.”

This new understanding may help the further development of these materials, which are easily reduced to nanoparticles; these are finding use in catalytic oxidation and reduction reactions associated with regulation of noxious emissions from motor vehicles.

The research is supported by the U.S. Department of Energy Office of Science through the Ames Laboratory.

The Ames Laboratory is a U.S. Department of Energy Office of Science national laboratory operated by Iowa State University. The Ames Laboratory creates innovative materials, technologies and energy solutions. We use our expertise, unique capabilities and interdisciplinary collaborations to solve global problems.

DOE’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, please visit

Laura Millsaps | EurekAlert!
Further information:

More articles from Materials Sciences:

nachricht Custom sequences for polymers using visible light
22.03.2018 | Tokyo Metropolitan University

nachricht The search for dark matter widens
21.03.2018 | American Institute of Physics

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Researchers Discover New Anti-Cancer Protein

An international team of researchers has discovered a new anti-cancer protein. The protein, called LHPP, prevents the uncontrolled proliferation of cancer cells in the liver. The researchers led by Prof. Michael N. Hall from the Biozentrum, University of Basel, report in “Nature” that LHPP can also serve as a biomarker for the diagnosis and prognosis of liver cancer.

The incidence of liver cancer, also known as hepatocellular carcinoma, is steadily increasing. In the last twenty years, the number of cases has almost doubled...

Im Focus: Researchers at Fraunhofer monitor re-entry of Chinese space station Tiangong-1

In just a few weeks from now, the Chinese space station Tiangong-1 will re-enter the Earth's atmosphere where it will to a large extent burn up. It is possible that some debris will reach the Earth's surface. Tiangong-1 is orbiting the Earth uncontrolled at a speed of approx. 29,000 km/h.Currently the prognosis relating to the time of impact currently lies within a window of several days. The scientists at Fraunhofer FHR have already been monitoring Tiangong-1 for a number of weeks with their TIRA system, one of the most powerful space observation radars in the world, with a view to supporting the German Space Situational Awareness Center and the ESA with their re-entry forecasts.

Following the loss of radio contact with Tiangong-1 in 2016 and due to the low orbital height, it is now inevitable that the Chinese space station will...

Im Focus: Alliance „OLED Licht Forum“ – Key partner for OLED lighting solutions

Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology FEP, provider of research and development services for OLED lighting solutions, announces the founding of the “OLED Licht Forum” and presents latest OLED design and lighting solutions during light+building, from March 18th – 23rd, 2018 in Frankfurt a.M./Germany, at booth no. F91 in Hall 4.0.

They are united in their passion for OLED (organic light emitting diodes) lighting with all of its unique facets and application possibilities. Thus experts in...

Im Focus: Mars' oceans formed early, possibly aided by massive volcanic eruptions

Oceans formed before Tharsis and evolved together, shaping climate history of Mars

A new scenario seeking to explain how Mars' putative oceans came and went over the last 4 billion years implies that the oceans formed several hundred million...

Im Focus: Tiny implants for cells are functional in vivo

For the first time, an interdisciplinary team from the University of Basel has succeeded in integrating artificial organelles into the cells of live zebrafish embryos. This innovative approach using artificial organelles as cellular implants offers new potential in treating a range of diseases, as the authors report in an article published in Nature Communications.

In the cells of higher organisms, organelles such as the nucleus or mitochondria perform a range of complex functions necessary for life. In the networks of...

All Focus news of the innovation-report >>>



Industry & Economy
Event News

Virtual reality conference comes to Reutlingen

19.03.2018 | Event News

Ultrafast Wireless and Chip Design at the DATE Conference in Dresden

16.03.2018 | Event News

International Tinnitus Conference of the Tinnitus Research Initiative in Regensburg

13.03.2018 | Event News

Latest News

Modular safety concept increases flexibility in plant conversion

22.03.2018 | Trade Fair News

New interactive map shows climate change everywhere in world

22.03.2018 | Earth Sciences

New technologies and computing power to help strengthen population data

22.03.2018 | Earth Sciences

Science & Research
Overview of more VideoLinks >>>