Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Finding hope in a meltdown

20.09.2010
Theoretical physicists find evidence of a new state of matter in a simple oxide

Symmetry is a fundamental concept in physics. Our ‘standard model’ of particle physics, for example, predicts that matter and anti-matter should have been created in equal amounts at the big bang, yet our existing universe is mostly matter. Such a discrepancy between the symmetry of known physical laws, and what we actually observe, are often the inspiration for realizing that new interactions are important or that new phases of matter can exist.

Shigeki Onoda, a theorist at the RIKEN Advanced Science Institute in Wako, recognized that experimentalists at The University of Tokyo had possibly discovered a new state of matter, called a ‘chiral spin liquid’ when they reported evidence of time-reversal symmetry breaking1—a difference between the trajectory of a particle moving along one path or its inverse—in the oxide called Pr2Ir2O7. If a material is magnetic, or in a magnetic field, its electrons will not obey time reversal symmetry; but in Pr2Ir2O7, neither contribution was present to explain what the experimentalists had observed.

Now, Onoda and colleague Yoichi Tanaka have explained how a chiral spin liquid could emerge from so-called ‘quantum spin fluctuations’—the motion of spins that occurs even at absolute zero2. “The possibility of a chiral spin liquid was first proposed twenty years ago and many physicists had lost hope to find it,” explains Onoda. “This is a revival of a phase that was found in a totally different system than where it was first expected.”

The interesting properties of Pr2Ir2O7 are rooted in its crystal structure, called a pyrochlore lattice: four praseodymium (Pr) ions, each of which carries a magnetic ‘spin’, form a tetrahedral cage around an oxygen (O) ion. At low temperatures, the spins of materials with this structure often ‘freeze’ into what is called a ‘spin ice’ because of its similarity to the way hydrogen ions form around oxygen in water ice.

Onoda and Tanaka predict, however, that the quantum fluctuations in the spins melt the spin ice structure of Pr2Ir2O7. They proposed a realistic model of Pr spins on a pyrochlore lattice and suggested that both the geometry of the crystal and the small size of the spin on the Pr ion allowed the quantum fluctuations to grow so large that they melted the spin ice into a chiral spin liquid.

If their prediction is correct, Pr2Ir2O7 will be the first material in which one can study this new state of matter.

The corresponding author for this highlight is based at the Condensed Matter Theory Laboratory, RIKEN Advanced Science Institute

Journal information

1. Machida, Y., Nakatsuji, S., Onoda, S., Tayama, T. & Sakakibara, T. Time-reversal symmetry breaking and spontaneous Hall effect without magnetic dipole order. Nature 463, 210–213 (2010).

2. Onoda, S. & Tanaka, Y. Quantum melting of spin ice: Emergent cooperative quadrupole and chirality. Physical Review Letters 105, 047201 (2010).

gro-pr | Research asia research news
Further information:
http://www.rikenresearch.riken.jp/eng/research/6392
http://www.researchsea.com

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

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

7th International Conference on Crystalline Silicon Photovoltaics in Freiburg on April 3-5, 2017

03.04.2017 | Event News

 
Latest News

Bare bones: Making bones transparent

27.04.2017 | Life Sciences

Study offers new theoretical approach to describing non-equilibrium phase transitions

27.04.2017 | Physics and Astronomy

From volcano's slope, NASA instrument looks sky high and to the future

27.04.2017 | Earth Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>