Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Escape from frustration

26.01.2009
When the bonds between atoms suddenly alter in strength, structural changes in symmetry result

Everyone prefers to avoid the frustration of failing to achieve a desired outcome. Now it seems this even applies to materials and the arrangement of their atomic magnets, referred to as spins.

Researchers from RIKEN’s Nishina Center for Accelerator-Based Science in Wako, in collaboration with researchers from the University of Hyogo and Kyoto University, have uncovered an intriguing interplay between the arrangement of atomic spins and atomic interactions in the metallic compound Mo3Sb7.

The molybdenum (Mo) atoms in Mo3Sb7 crystals are arranged in octahedra. Unusually, the atomic bonds between the Mo atoms at the tips of the octahedra are stronger than between the Mo atoms in the plane. This leads to the formation of ‘dumbbells’ of Mo pairs along the three main crystal directions (Fig. 1). “The unusual arrangement between the dumbbells and the other Mo atoms makes this material unique and interesting to study,” comments Isao Watanabe from the research team.

Of particular interest is a sudden structural change that occurs at temperatures below 50 K (-223.15 °C). The origin of this phase transition has now been unveiled by a number of experiments that probe the magnetic and electric properties of the Mo atoms (1). These measurements present clear evidence that the phase transition is accompanied by symmetry changes in the crystal.

The symmetry changes are triggered by the spins associated with Mo atoms. The researchers found that an unusual competition in interaction between the Mo atoms takes place. At the phase transition, the strength of the interaction between the Mo atoms in the octahedra becomes comparable to the bond between the Mo atoms in the dumbbells. Consequently, the Mo atomic spins then begin to arrange in an up-and-down fashion along the entire crystal rather than within the dumbbells. However, owing to the particularities of the three-dimensional crystal structure, a periodic up-and-down arrangement, which is homogeneous across the entire crystal, is impossible. Frustration is the result.

To break this frustration the Mo octahedra elongate in one direction, breaking the crystal symmetry. This in turn finally allows the Mo dumbbells to order themselves periodically throughout the crystal in an arrangement termed a ‘valence bond crystal’.

The unusual competition of the atomic bonds between the Mo atoms in Mo3Sb7 has led to dramatic consequences involving crystallographic, electronic and magnetic properties. “This is the first example of its kind and we expect that this opens a new field to study similarly complex systems,” say Watanabe and his colleagues.

Reference

1. Koyama, T., Yamashita, H., Takahashi, Y, Kohara, T., Watanabe, I., Tabata, Y. & Nakamura, H. Frustration-induced valence bond crystal and its melting in Mo3Sb7. Physical Review Letters 101, 126404 (2008).

Saeko Okada | ResearchSEA
Further information:
http://www.rikenresearch.riken.jp/research/629/
http://www.researchsea.com

More articles from Physics and Astronomy:

nachricht Measured for the first time: Direction of light waves changed by quantum effect
24.05.2017 | Vienna University of Technology

nachricht Physicists discover mechanism behind granular capillary effect
24.05.2017 | University of Cologne

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: A quantum walk of photons

Physicists from the University of Würzburg are capable of generating identical looking single light particles at the push of a button. Two new studies now demonstrate the potential this method holds.

The quantum computer has fuelled the imagination of scientists for decades: It is based on fundamentally different phenomena than a conventional computer....

Im Focus: Turmoil in sluggish electrons’ existence

An international team of physicists has monitored the scattering behaviour of electrons in a non-conducting material in real-time. Their insights could be beneficial for radiotherapy.

We can refer to electrons in non-conducting materials as ‘sluggish’. Typically, they remain fixed in a location, deep inside an atomic composite. It is hence...

Im Focus: Wafer-thin Magnetic Materials Developed for Future Quantum Technologies

Two-dimensional magnetic structures are regarded as a promising material for new types of data storage, since the magnetic properties of individual molecular building blocks can be investigated and modified. For the first time, researchers have now produced a wafer-thin ferrimagnet, in which molecules with different magnetic centers arrange themselves on a gold surface to form a checkerboard pattern. Scientists at the Swiss Nanoscience Institute at the University of Basel and the Paul Scherrer Institute published their findings in the journal Nature Communications.

Ferrimagnets are composed of two centers which are magnetized at different strengths and point in opposing directions. Two-dimensional, quasi-flat ferrimagnets...

Im Focus: World's thinnest hologram paves path to new 3-D world

Nano-hologram paves way for integration of 3-D holography into everyday electronics

An Australian-Chinese research team has created the world's thinnest hologram, paving the way towards the integration of 3D holography into everyday...

Im Focus: Using graphene to create quantum bits

In the race to produce a quantum computer, a number of projects are seeking a way to create quantum bits -- or qubits -- that are stable, meaning they are not much affected by changes in their environment. This normally needs highly nonlinear non-dissipative elements capable of functioning at very low temperatures.

In pursuit of this goal, researchers at EPFL's Laboratory of Photonics and Quantum Measurements LPQM (STI/SB), have investigated a nonlinear graphene-based...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Marine Conservation: IASS Contributes to UN Ocean Conference in New York on 5-9 June

24.05.2017 | Event News

AWK Aachen Machine Tool Colloquium 2017: Internet of Production for Agile Enterprises

23.05.2017 | Event News

Dortmund MST Conference presents Individualized Healthcare Solutions with micro and nanotechnology

22.05.2017 | Event News

 
Latest News

Physicists discover mechanism behind granular capillary effect

24.05.2017 | Physics and Astronomy

Measured for the first time: Direction of light waves changed by quantum effect

24.05.2017 | Physics and Astronomy

Marine Conservation: IASS Contributes to UN Ocean Conference in New York on 5-9 June

24.05.2017 | Event News

VideoLinks
B2B-VideoLinks
More VideoLinks >>>