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 Engineering team images tiny quasicrystals as they form
18.08.2017 | Cornell University

nachricht Astrophysicists explain the mysterious behavior of cosmic rays
18.08.2017 | Moscow Institute of Physics and 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: Fizzy soda water could be key to clean manufacture of flat wonder material: Graphene

Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.

As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...

Im Focus: Exotic quantum states made from light: Physicists create optical “wells” for a super-photon

Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.

Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...

Im Focus: Circular RNA linked to brain function

For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.

While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...

Im Focus: RAVAN CubeSat measures Earth's outgoing energy

An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.

The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...

Im Focus: Scientists shine new light on the “other high temperature superconductor”

A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.

Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Call for Papers – ICNFT 2018, 5th International Conference on New Forming Technology

16.08.2017 | Event News

Sustainability is the business model of tomorrow

04.08.2017 | Event News

Clash of Realities 2017: Registration now open. International Conference at TH Köln

26.07.2017 | Event News

 
Latest News

A Map of the Cell’s Power Station

18.08.2017 | Life Sciences

Engineering team images tiny quasicrystals as they form

18.08.2017 | Physics and Astronomy

Researchers printed graphene-like materials with inkjet

18.08.2017 | Materials Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>