Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Emerging research suggests a new paradigm for "unconventional superconductors"


An international team of scientists has reported the first experimental observation of the quantum critical point (QCP) in the extensively studied “unconventional superconductor” TiSe2, finding that it does not reside as predicted within the superconducting dome of the phase diagram, but rather at a full GPa higher in pressure.

The surprising result, reported in Nature Physics, suggests that the emergence of superconductivity in TiSe2 isn’t associated with the melting of a charge density wave (CDW), as prevailing theory holds; in fact the CDW’s amplitude decreases under increasing pressure, but does not disappear at zero resistance.

Artist's conception of charge density wave domain walls in TiSe2 and the emergence of superconductivity through their quantum fluctuations. Image by Young Il Joe

The researchers find that the emergence of superconductivity in this material is connected rather with the formation of domain walls between commensurate and incommensurate phase transitions. The discovery of this new phase boundary has implications for our understanding of superconducting behavior.

The experiments, conducted by Young Il Joe, a graduate student working with condensed matter physicist Peter Abbamonte, employed a novel X-ray scattering technique at the Cornell High Energy Synchrotron Source (CHESS) to obtain the first ever measurements of the degree of commensurability of the CDW order parameter.

In this, the researchers took advantage of the harmonics of the diffractive optics—usually filtered out in X-ray experiments—to take two readings simultaneously. The wavelengths of two simultaneous photon beams were carefully calibrated, one to measure the periodicity of the crystal lattice, the other to measure the periodicity of the electrons, and compare the two.

At low energies, the CDW was found to be commensurate, as expected, but above the superconducting dome, incommensurate behavior emerged as the temperature was increased. The superconducting characteristics of TiSe2 are typical of other unconventional superconducting materials that exhibit the universal phase diagram, suggesting a fundamental connection between unconventional superconductivity and the quantum dynamics of domain walls.

This work sheds new light on our understanding to the theorized connection between superconductivity and other ordered states, such as charge density wave (CDW), antiferromagnetism, or stripe order and could contribute to the eventual development of better superconducting materials, and ultimately to the possible invention of room-temperature superconductors.

The X-ray experiments were supported by the U.S. Department of Energy under Grant No. DE-FG02-06ER46285. Young Il Joe, Shi Yuan, and Lance Cooper grew the 1-TiSe2 crystals at the Frederick Seitz Materials Research Laboratory at the University of Illinois at Urbana-Champaign with support from DOE Grant No. DE-FG02-07ER46453. Use of the CHESS was supported by the National Science Foundation and the National Institutes of Health/National Institute of General Medical Sciences under NSF award DMR-0936384.

T.C. Chiang’s contributions were supported by DOE Grant No. DE-FG02-07ER46383. The conclusions presented are those of the scientists and not necessarily those of the funding agencies. Contact: Peter Abbamonte, Department of Physics, University of Illinois at Urbana-Champaign, 217/244-4861. Siv Schwink, communications coordinator, Department of Physics, University of Illinois at Urbana-Champaign, 217/300-2201.

Peter Abbamonte | EurekAlert!
Further information:

More articles from Physics and Astronomy:

nachricht Graphene microphone outperforms traditional nickel and offers ultrasonic reach
27.11.2015 | Institute of Physics

nachricht Tracking down the 'missing' carbon from the Martian atmosphere
25.11.2015 | California Institute of Technology

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: Climate study finds evidence of global shift in the 1980s

Planet Earth experienced a global climate shift in the late 1980s on an unprecedented scale, fuelled by anthropogenic warming and a volcanic eruption, according to new research published this week.

Scientists say that a major step change, or ‘regime shift’, in the Earth’s biophysical systems, from the upper atmosphere to the depths of the ocean and from...

Im Focus: Innovative Photovoltaics – from the Lab to the Façade

Fraunhofer ISE Demonstrates New Cell and Module Technologies on its Outer Building Façade

The Fraunhofer Institute for Solar Energy Systems ISE has installed 70 photovoltaic modules on the outer façade of one of its lab buildings. The modules were...

Im Focus: Lactate for Brain Energy

Nerve cells cover their high energy demand with glucose and lactate. Scientists of the University of Zurich now provide new support for this. They show for the first time in the intact mouse brain evidence for an exchange of lactate between different brain cells. With this study they were able to confirm a 20-year old hypothesis.

In comparison to other organs, the human brain has the highest energy requirements. The supply of energy for nerve cells and the particular role of lactic acid...

Im Focus: Laser process simulation available as app for first time

In laser material processing, the simulation of processes has made great strides over the past few years. Today, the software can predict relatively well what will happen on the workpiece. Unfortunately, it is also highly complex and requires a lot of computing time. Thanks to clever simplification, experts from Fraunhofer ILT are now able to offer the first-ever simulation software that calculates processes in real time and also runs on tablet computers and smartphones. The fast software enables users to do without expensive experiments and to find optimum process parameters even more effectively.

Before now, the reliable simulation of laser processes was a job for experts. Armed with sophisticated software packages and after many hours on computer...

Im Focus: Quantum Simulation: A Better Understanding of Magnetism

Heidelberg physicists use ultracold atoms to imitate the behaviour of electrons in a solid

Researchers at Heidelberg University have devised a new way to study the phenomenon of magnetism. Using ultracold atoms at near absolute zero, they prepared a...

All Focus news of the innovation-report >>>



Event News

Fraunhofer’s Urban Futures Conference: 2 days in the city of the future

25.11.2015 | Event News

Gluten oder nicht Gluten? Überempfindlichkeit auf Weizen kann unterschiedliche Ursachen haben

17.11.2015 | Event News

Art Collection Deutsche Börse zeigt Ausstellung „Traces of Disorder“

21.10.2015 | Event News

Latest News

Siemens to supply 126 megawatts to onshore wind power plants in Scotland

27.11.2015 | Press release

Two decades of training students and experts in tracking infectious disease

27.11.2015 | Life Sciences

Coming to a monitor near you: A defect-free, molecule-thick film

27.11.2015 | Materials Sciences

More VideoLinks >>>