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 Study offers new theoretical approach to describing non-equilibrium phase transitions
27.04.2017 | DOE/Argonne National Laboratory

nachricht SwRI-led team discovers lull in Mars' giant impact history
26.04.2017 | Southwest Research Institute

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: Making lightweight construction suitable for series production

More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.

Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...

Im Focus: Wonder material? Novel nanotube structure strengthens thin films for flexible electronics

Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.

"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...

Im Focus: Deep inside Galaxy M87

The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.

Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...

Im Focus: A Quantum Low Pass for Photons

Physicists in Garching observe novel quantum effect that limits the number of emitted photons.

The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...

Im Focus: Microprocessors based on a layer of just three atoms

Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.

Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Fighting drug resistant tuberculosis – InfectoGnostics meets MYCO-NET² partners in Peru

28.04.2017 | Event News

Expert meeting “Health Business Connect” will connect international medical technology companies

20.04.2017 | Event News

Wenn der Computer das Gehirn austrickst

18.04.2017 | Event News

 
Latest News

How Plants Form Their Sugar Transport Routes

28.04.2017 | Life Sciences

Protein 'spy' gains new abilities

28.04.2017 | Life Sciences

Researchers unravel the social network of immune cells

28.04.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>