Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

A lack of order

16.08.2010
A comparative study of two closely related organic insulators highlights the unusual properties of quantum spin liquids

A growing body of experimental evidence is lending support to the theory that an exotic state of matter called a quantum spin liquid actually exists. In a quantum spin liquid, the way electrons spin on their axes lacks any sense of organization throughout the material—even at temperatures approaching absolute zero, where order tends to reign supreme. However, definitive proof has proved elusive, particularly in two-dimensional systems.

Signatures of a quantum spin liquid have now been observed in an organic insulator by Reizo Kato at the RIKEN Advanced Science Institute, Wako, working in collaboration with researchers from Kyoto University and the Japan Science and Technology Agency1.

In a quantum spin liquid, the magnetic arrangement of the material is incompatible with the underlying crystal geometry, thus preventing the spin from showing any order (Fig. 1). “This leads to liquid-like properties among the spins, even at absolute zero temperature,” explains Kato. In contrast, molecules in ice arrange into a crystalline lattice—a pattern maintained throughout the material.

The team compared two closely related organic insulators EtMe3Sb[Pd(dmit)2]2 (abbreviated as dmit-131) and Et2Me2Sb[Pd(dmit)2]2 (abbreviated as dmit-221). Scientists previously proposed that dmit-131 may show quantum-spin-liquid state properties. Indeed, using nuclear magnetic resonance measurements, scientists have never identified any long-range magnetic order at temperatures as low as 19 millikelvin. The reason for this remains unclear. The crystal structure of dmit-221 is very similar; however, it exhibits a charge-ordered state. Kato and colleagues therefore thought that a comparison between the two should reveal any properties particular to quantum spin liquids.

The researchers measured the thermal conductivity at temperatures between 10 and 0.1 Kelvin, since one of the most important experimental parameters is the thermal conductivity divided by the temperature. In dmit-221, this parameter approaches zero as the temperature gets closer to absolute zero. “This is typical behavior of insulators where lattice vibrations carry thermal energy,” says Kato. In dmit-331, however, they extrapolated the parameter to be nonzero at 0 Kelvin. “This is more akin to metallic behavior where free electrons carry the thermal energy.” This indicates the presence of so-called ‘gapless excitations’, meaning that there is no energy gap between the ground state and excited states. However, there is also some evidence for spin-gap-like excitations.

These results indicate that this system is a quantum spin liquid with a dual nature. “The next step is to address the fundamental question of whether a quantum spin liquid undergoes instabilities other than classical ordering,” Kato notes.

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

Journal information

1. 1.Yamashita, M., Nakata, N., Senshu, Y., Nagata, M., Yamamoto, H.M., Kato, R., Shibauchi, T. & Matsuda, Y. Highly mobile gapless excitations in a two-dimensional candidate quantum spin liquid. Science 328, 1246–1248 (2010). article

gro-pr | Research asia research news
Further information:
http://www.rikenresearch.riken.jp/eng/research/6365
http://www.researchsea.com

More articles from Studies and Analyses:

nachricht Antarctic Ice Sheet mass loss has increased
14.06.2018 | Technische Universität Dresden

nachricht WAKE-UP provides new treatment option for stroke patients | International study led by UKE
17.05.2018 | Universitätsklinikum Hamburg-Eppendorf

All articles from Studies and Analyses >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: AchemAsia 2019 will take place in Shanghai

Moving into its fourth decade, AchemAsia is setting out for new horizons: The International Expo and Innovation Forum for Sustainable Chemical Production will take place from 21-23 May 2019 in Shanghai, China. With an updated event profile, the eleventh edition focusses on topics that are especially relevant for the Chinese process industry, putting a strong emphasis on sustainability and innovation.

Founded in 1989 as a spin-off of ACHEMA to cater to the needs of China’s then developing industry, AchemAsia has since grown into a platform where the latest...

Im Focus: First real-time test of Li-Fi utilization for the industrial Internet of Things

The BMBF-funded OWICELLS project was successfully completed with a final presentation at the BMW plant in Munich. The presentation demonstrated a Li-Fi communication with a mobile robot, while the robot carried out usual production processes (welding, moving and testing parts) in a 5x5m² production cell. The robust, optical wireless transmission is based on spatial diversity; in other words, data is sent and received simultaneously by several LEDs and several photodiodes. The system can transmit data at more than 100 Mbit/s and five milliseconds latency.

Modern production technologies in the automobile industry must become more flexible in order to fulfil individual customer requirements.

Im Focus: Sharp images with flexible fibers

An international team of scientists has discovered a new way to transfer image information through multimodal fibers with almost no distortion - even if the fiber is bent. The results of the study, to which scientist from the Leibniz-Institute of Photonic Technology Jena (Leibniz IPHT) contributed, were published on 6thJune in the highly-cited journal Physical Review Letters.

Endoscopes allow doctors to see into a patient’s body like through a keyhole. Typically, the images are transmitted via a bundle of several hundreds of optical...

Im Focus: Photoexcited graphene puzzle solved

A boost for graphene-based light detectors

Light detection and control lies at the heart of many modern device applications, such as smartphone cameras. Using graphene as a light-sensitive material for...

Im Focus: Water is not the same as water

Water molecules exist in two different forms with almost identical physical properties. For the first time, researchers have succeeded in separating the two forms to show that they can exhibit different chemical reactivities. These results were reported by researchers from the University of Basel and their colleagues in Hamburg in the scientific journal Nature Communications.

From a chemical perspective, water is a molecule in which a single oxygen atom is linked to two hydrogen atoms. It is less well known that water exists in two...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Munich conference on asteroid detection, tracking and defense

13.06.2018 | Event News

2nd International Baltic Earth Conference in Denmark: “The Baltic Sea region in Transition”

08.06.2018 | Event News

ISEKI_Food 2018: Conference with Holistic View of Food Production

05.06.2018 | Event News

 
Latest News

A sprinkle of platinum nanoparticles onto graphene makes brain probes more sensitive

15.06.2018 | Materials Sciences

100 % Organic Farming in Bhutan – a Realistic Target?

15.06.2018 | Ecology, The Environment and Conservation

Perovskite-silicon solar cell research collaboration hits 25.2% efficiency

15.06.2018 | Power and Electrical Engineering

VideoLinks
Science & Research
Overview of more VideoLinks >>>