Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Spin lattices enter a new phase

20.04.2009
RIKEN scientists, in collaboration with researchers at the University of Tokyo, Japan, and Sungkyunkwan University, Korea, have unveiled the possible existence of a new magnetic phase in the spatial arrangements of electron spins

A new ordered phase is predicted for geometrically frustrated spin systems even in the absence of magnetic order

RIKEN scientists, in collaboration with researchers at the University of Tokyo, Japan, and Sungkyunkwan University, Korea, have unveiled the possible existence of a new magnetic phase in the spatial arrangements of electron spins (1). The new arrangement is considered to be the combination of two unconventional types of order.

Spin, in this context, is the smallest magnetic moment associated with an electron and can point in any direction. In most solid structures, the spins of electrons sitting on different atoms will tend to point in such a way that neighboring spins point in opposite, or ‘anti-parallel’ directions. This gives rise to the so-called antiferromagnetic phase. There are, however, some atomic structures for which this is not possible, and they are called geometrically frustrated structures. Triangular lattices, including the compounds ê-(BEDT-TTF)2Cu2(CN)3 and NiGa2S4, are common examples of geometrically frustrated structures.

As team-member Shigeki Onoda from the RIKEN Advanced Science Institute in Wako explains, the spins interact among themselves and with the natural vibration of the lattice. This combined interaction can give rise to unusual types of order. One example is the helical order, in which spins rotate with respect to one another, but in an ordered way. The helical order is a type of chiral order: as in all chiral systems, it cannot be superimposed on its mirror image. Another example is the nematic order in which the orientation angle of the spins is fixed, but keep flipping their direction.

The researchers studied theoretically the phase diagram of a triangular lattice in which spins can point in any direction in the plane. The mutual interaction between spins has two components: one that is usually responsible for the emergence of helical order, and one that leads to nematic order. Until now, however, no-one had considered the combination of both.

The team’s calculations show interesting results in the case in which the nematic component is predominant. When the temperature rises—increasing the lattice vibrations—the helical order is replaced by a new chiral phase, in which the spins flip in time, similar to the nematic case. According to Onoda, this chiral–nematic order could be used in applications. The chirality allows rotating the polarization of a transmitted laser beam. By varying the external conditions, such as external fields, pressure, or temperature, it could be possible to switch the chirality—and the polarization rotation—on and off, effectively creating a functional optical device.

References

Park, J.-H., Onoda, S., Nagaosa, N. & Han, J.H. Nematic and chiral order for planar spins on a triangular lattice. Physical Review Letters 101, 167202 (2008).

The corresponding author for this highlight is based at the RIKEN Condensed Matter Theory Laboratory

Saeko Okada | Research asia research news
Further information:
http://www.rikenresearch.riken.jp/research/672/
http://www.researchsea.com

More articles from Physics and Astronomy:

nachricht Astronomers find unexpected, dust-obscured star formation in distant galaxy
24.03.2017 | University of Massachusetts at Amherst

nachricht Gravitational wave kicks monster black hole out of galactic core
24.03.2017 | NASA/Goddard Space Flight Center

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: Giant Magnetic Fields in the Universe

Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.

The results will be published on March 22 in the journal „Astronomy & Astrophysics“.

Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...

Im Focus: Tracing down linear ubiquitination

Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.

Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...

Im Focus: Perovskite edges can be tuned for optoelectronic performance

Layered 2D material improves efficiency for solar cells and LEDs

In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...

Im Focus: Polymer-coated silicon nanosheets as alternative to graphene: A perfect team for nanoelectronics

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...

Im Focus: Researchers Imitate Molecular Crowding in Cells

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Land Use Symposium ILUS 2017: Call for Abstracts and Registration open

20.03.2017 | Event News

CONNECT 2017: International congress on connective tissue

14.03.2017 | Event News

ICTM Conference: Turbine Construction between Big Data and Additive Manufacturing

07.03.2017 | Event News

 
Latest News

Big data approach to predict protein structure

27.03.2017 | Life Sciences

Parallel computation provides deeper insight into brain function

27.03.2017 | Life Sciences

Weather extremes: Humans likely influence giant airstreams

27.03.2017 | Earth Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>