Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Resistivity switch is window to role of magnetism in iron-based superconductors

06.06.2013
Physicists at the U.S. Department of Energy’s Ames Laboratory have discovered surprising changes in electrical resistivity in iron-based superconductors. The findings, reported in Nature Communications, offer further evidence that magnetism and superconductivity are closely related in this class of novel superconductors.
“We found that the directions of smallest and largest resistivity within the conducting layers are significantly dependent on the composition of the compounds, and in some compositions, they change sign, or, in other words, electric current flows easier in the direction that was originally more difficult” said Ames Laboratory faculty scientist Ruslan Prozorov. “This change can only be explained if the underlying magnetic behavior is intimately connected to superconductivity.”

Understanding the basic physics behind iron-based superconductivity may someday make it possible to use them for super-efficient energy technologies.

Erick Blomberg, an Ames Laboratory graduate research assistant, spearheaded the research under the guidance of Prozorov and Ames Laboratory scientist Makariy Tanatar. The team studied resistivity in barium-iron-arsenide compounds with different chemical substitutions, which allowed for probing electronic properties throughout the entire regime in which magnetism and superconductivity coexist.

In conventional superconductors, magnetism and superconductivity do not coexist and one suppresses another. In contrast, some iron-based superconductors show significant overlap between magnetism and superconductivity, which allows for unique measurements of their properties in the coexistence region.

“But there is a complication,” said Prozorov, who is also an Iowa State University professor in the Department of Physics & Astronomy. “In the coexistence region, the crystal structure of barium-iron-arsenide crystals is such that the crystal splits into the structural domains (also known as structural twins), which makes studying directional electronic properties difficult.

To eliminate the structural domains, the team developed a technique in which single crystals are physically pulled apart. A sample is suspended by wires in a horseshoe-shaped bracket, which can be mechanically stretched. This assembly is then placed into a small liquid helium cryostat to reach temperatures where magnetism and superconductivity coexist. Polarized optical microscopy is used to distinguish between different structural domains to verify that the samples are in the detwinned (without fragmented domains) state. Electric resistivity is then measured.

Blomberg and colleagues studied a series of samples, covering a precise range of compositions, provided by Nanjing University’s Hai-Hu Wen.

“In this case, making chemical substitutions was, in effect, taking electrons away from the compound or adding electrons to the compound,” said Blomberg, who will soon receive a PhD in condensed matter physics from Iowa State University. “And as you take electrons away, at a certain point the direction in which it was harder for electricity to flow becomes the direction it was easier for it to flow.”

Theoretical predictions made by physicists Jörg Schmalian and Rafael Fernandez (both former Ames Laboratory scientists) along with Naval Research Lab’s Igor Mazin and Michelle Johannes, closely matched the experimental findings.

The research is supported by the U.S. Department of Energy Office of Science. 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 the Office of Science website at science.energy.gov/.

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.
Contacts:
Ruslan Prozorov, Materials Sciences and Engineering, 515-294-9901
Breehan Gerleman Lucchesi, Public Affairs, 515-294-9750

Breehan Gerleman Lucchesi | EurekAlert!
Further information:
http://www.ameslab.gov

More articles from Physics and Astronomy:

nachricht Computer model predicts how fracturing metallic glass releases energy at the atomic level
20.07.2018 | American Institute of Physics

nachricht What happens when we heat the atomic lattice of a magnet all of a sudden?
18.07.2018 | Forschungsverbund Berlin

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

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

Im Focus: Future electronic components to be printed like newspapers

A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.

The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...

Im Focus: First evidence on the source of extragalactic particles

For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.

To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...

Im Focus: Magnetic vortices: Two independent magnetic skyrmion phases discovered in a single material

For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.

Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...

Im Focus: Breaking the bond: To take part or not?

Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.

A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...

Im Focus: New 2D Spectroscopy Methods

Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.

"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Leading experts in Diabetes, Metabolism and Biomedical Engineering discuss Precision Medicine

13.07.2018 | Event News

Conference on Laser Polishing – LaP: Fine Tuning for Surfaces

12.07.2018 | Event News

11th European Wood-based Panel Symposium 2018: Meeting point for the wood-based materials industry

03.07.2018 | Event News

 
Latest News

A smart safe rechargeable zinc ion battery based on sol-gel transition electrolytes

20.07.2018 | Power and Electrical Engineering

Reversing cause and effect is no trouble for quantum computers

20.07.2018 | Information Technology

Princeton-UPenn research team finds physics treasure hidden in a wallpaper pattern

20.07.2018 | Materials Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>