Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Nagoya physicists resolve long-standing mystery of structure-less transition

21.08.2017

Nagoya University-led team of physicists use a synchrotron radiation X-ray source to probe a so-called 'structure-less' transition and develop a new understanding of molecular conductors

We normally associate conduction of electricity with metals. However, some of the high measured conductivities are found in certain organic molecular crystals. Metallic, semiconducting and even superconducting properties can be achieved in these materials, which have interested scientists for decades.


Electron density distribution of the frontier orbital of a TMTTF molecule. Electrons of the constituent atoms of the molecule can be considered as either core electrons, which have no interactions with the surroundings, or electrons of frontier orbitals, which determine many physical properties of the molecule. We succeeded in visualizing the frontier molecular orbital distribution of a TMTTF by precise structural analysis using a core differential Fourier synthesis (CDFS) method.

Credit: Shunsuke Kitou

Changing temperature or pressure causes phase transitions in the crystal structure of molecular conductors and their related conduction properties. Scientists can usually determine the crystal structure using X-ray diffraction. However, structural change accompanying phase transition in a particular organic crystal (TMTTF)2PF6 has defied examination for almost 40 years.

Now, a research team at Nagoya University has finally explained the mysterious structural changes of this phase transition and its related electronic behavior.

"Researchers have questioned that the TMTTF (tetramethyltetrathiafulvalene) salt shows a charge disproportionation transition at 67 Kelvin but no relevant changes in its crystal structure. This transition is a long-standing mystery known as a 'structure-less transition'," explains lead author Shunsuke Kitou.

TMTTF is an organic donor that is also found in some organic superconductors. Just above the temperature that liquid nitrogen freezes, this organic crystal behaves as an insulator. But as the temperature is lowered it goes through electronic and magnetic changes.

Until now these structural changes were too small to measure directly. Using the X-ray source at SPring8, in Hyogo Japan, the team could precisely determine the crystal structure at each stage. The structure-less transition involves the formation of a two-dimensional Wigner crystal, based on a change in the distribution pattern of electrons in the structure.

"We have precisely characterized the subtle structural changes across this transition and finally provided a complete physical explanation for the apparent unchanging structure of this organic conductor," says group leader Hiroshi Sawa. "Accurate crystallographic data is still lacking for many organic conductors and we hope our findings will inspire other groups to look more closely at these systems. A better understanding of their complex behavior could pave the way to a range of new functional electronic materials."

###

The article, "Successive Dimensional Transition in (TMTTF)2PF6 Revealed by Synchrotron X-ray Diffraction," was published in Physical Review Letters. https://doi.org/10.1103/PhysRevLett.119.065701

Koomi Sung | EurekAlert!

More articles from Materials Sciences:

nachricht Shape-shifting sheets
21.08.2019 | Harvard John A. Paulson School of Engineering and Applied Sciences

nachricht New 3D interconnection technology for future wearable bioelectronics
15.08.2019 | Institute for Basic Science

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Hamburg and Kiel researchers observe spontaneous occurrence of skyrmions in atomically thin cobalt films

Since their experimental discovery, magnetic skyrmions - tiny magnetic knots - have moved into the focus of research. Scientists from Hamburg and Kiel have now been able to show that individual magnetic skyrmions with a diameter of only a few nanometres can be stabilised in magnetic metal films even without an external magnetic field. They report on their discovery in the journal Nature Communications.

The existence of magnetic skyrmions as particle-like objects was predicted 30 years ago by theoretical physicists, but could only be proven experimentally in...

Im Focus: Physicists create world's smallest engine

Theoretical physicists at Trinity College Dublin are among an international collaboration that has built the world's smallest engine - which, as a single calcium ion, is approximately ten billion times smaller than a car engine.

Work performed by Professor John Goold's QuSys group in Trinity's School of Physics describes the science behind this tiny motor.

Im Focus: Quantum computers to become portable

Together with the University of Innsbruck, the ETH Zurich and Interactive Fully Electrical Vehicles SRL, Infineon Austria is researching specific questions on the commercial use of quantum computers. With new innovations in design and manufacturing, the partners from universities and industry want to develop affordable components for quantum computers.

Ion traps have proven to be a very successful technology for the control and manipulation of quantum particles. Today, they form the heart of the first...

Im Focus: Towards an 'orrery' for quantum gauge theory

Experimental progress towards engineering quantized gauge fields coupled to ultracold matter promises a versatile platform to tackle problems ranging from condensed-matter to high-energy physics

The interaction between fields and matter is a recurring theme throughout physics. Classical cases such as the trajectories of one celestial body moving in the...

Im Focus: A miniature stretchable pump for the next generation of soft robots

Soft robots have a distinct advantage over their rigid forebears: they can adapt to complex environments, handle fragile objects and interact safely with humans. Made from silicone, rubber or other stretchable polymers, they are ideal for use in rehabilitation exoskeletons and robotic clothing. Soft bio-inspired robots could one day be deployed to explore remote or dangerous environments.

Most soft robots are actuated by rigid, noisy pumps that push fluids into the machines' moving parts. Because they are connected to these bulky pumps by tubes,...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

The power of thought – the key to success: CYBATHLON BCI Series 2019

16.08.2019 | Event News

4th Hybrid Materials and Structures 2020 28 - 29 April 2020, Karlsruhe, Germany

14.08.2019 | Event News

What will the digital city of the future look like? City Science Summit on 1st and 2nd October 2019 in Hamburg

12.08.2019 | Event News

 
Latest News

Making small intestine endoscopy faster with a pill-sized high-tech camera

23.08.2019 | Medical Engineering

More reliable operation offshore wind farms

23.08.2019 | Power and Electrical Engineering

Tracing the evolution of vision

23.08.2019 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>