Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

The ‘Hall’ mark of a quantum magnet

17.05.2010
The presence of exotic particles, called spinons, might now be detectable in a magnetic field, providing insight into quantum magnet properties

An important model to explain high-temperature superconductivity is the so-called ‘quantum spin liquid’. Scientists are therefore interested in understanding the low-energy excitations of this magnetic state.

Now, a theoretical study by a research team from RIKEN and the Massachusetts Institute of Technology, USA, has explained how the properties of spin liquids could be revealed by a simple heat-transfer experiment.

In an insulating magnetic crystal, the electronic spins are localized to the atoms that form the crystal lattice. For most such magnets, or antiferromagnets, the chemical bonds favor an arrangement where, at low temperatures, each spin points in a direction opposite to that of its neighbor. However, on a triangular lattice, such as the ‘Kagome lattice’, a spin cannot simultaneously be opposite to all of its neighbors. The spins in these magnets never order, even at very low temperatures—giving rise to the name quantum spin liquid.

“Spin liquids have an exotic electronic state because [their] electrons can effectively dissociate into distinguishable spin- and charge-carrying particles,” explains team-member Naoto Nagaosa from the RIKEN Advanced Science Institute, Wako. “The spin-carrying particle is called a spinon and determines the low-energy properties of the magnet.”

To date, however, few experiments have found spinons. Nagaosa and his collaborators explain how a method similar to the so-called ‘Hall measurement’—an indispensible technique for studying the properties of semiconductors—could be used to detect spinons.

In the classic version of the Hall measurement, a magnetic field is applied perpendicular to a charge-carrying current, causing positive charges to curve one way and negative charges the other. The deflection of the charges provides information about their properties, including their sign.

In the ‘thermal Hall effect’ considered by Nagaosa and his colleagues, temperature serves as the driving force to create a current—not of charges, but of magnetic excitations—that flow in a magnetic field. For a spin liquid, these excitations are the spinons. As in the classic Hall effect, a magnetic field will deflect these excitations, which will change the direction of the heat flow—an effect that experimentalists should be able to measure.

Nagaosa and his colleagues showed that while there is no thermal Hall effect in most conventional antiferromagnets, the presence of spinons in a spin liquid would result in a clear effect. This experimental probe could therefore become an important way to identify and study excitations of quantum magnets.

The corresponding author for this highlight is based at the Cross-Correlated Materials Research Group, RIKEN Advanced Science Institute

Journal information

1. Katsura, H., Nagaosa, N. & Lee, P.A. Theory of the thermal Hall effect in quantum magnets. Physical Review Letters 104, 066403 (2010).

gro-pr | Research asia research news
Further information:
http://www.rikenresearch.riken.jp/eng/research/6264
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

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

21.08.2017 | Materials Sciences

Chronic stress induces fatal organ dysfunctions via a new neural circuit

21.08.2017 | Health and Medicine

Scientists from the MSU studied new liquid-crystalline photochrom

21.08.2017 | Materials Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>