Featured Research

from universities, journals, and other organizations

Burying the hatchet in the laser lab

Date:
September 25, 2012
Source:
Christian-Albrechts-Universitaet zu Kiel
Summary:
Experts have been heavily discussing why exactly electrically insulating materials insulate as they do. Based on different mechanisms, a classification scheme for insulators has been in use since the 1960s -- a theoretical one. However, it has been yet impossible to distinctly classify all insulators due to a lack of suitable experimental approaches. A team of physicists has now developed a new method to distinguish different insulators unambiguously.

Experts have been heavily discussing why exactly electrically insulating materials insulate as they do. Based on different mechanisms, a classification scheme for insulators has been in use since the 1960s -- a theoretical one. However, it has been yet impossible to distinctly classify all insulators due to a lack of suitable experimental approaches. A team of physicists from Kiel University (Germany) and the University of Colorado in Boulder (USA) has now developed a new method to distinguish different insulators unambiguously.

Related Articles


The study was published in the online journal Nature Communications.

No notebook, no cell phone, no digital camera would be functional without electrical insulators. The hunt for precise knowledge about state-of-the-art or future insulators is just as rapid as the development of new, better electronic devices. For this reason, insulator research is currently one of the hottest topics in solid-state science.

Following the common scientific procedures in physics, such insulators are first described using universal equations and simulated by computer models. The theoretical results about materials then need to be verified by experiments in the lab. It is this experimental verification that failed for a number of insulators in the past. „For many years, expert discussions went round and round without any final answer about the insulator class," says project leader Kai Rossnagel from the Institute of Experimental and Applied Physics of Kiel University. The study presented now provides a completely new experimental approach to classifying the insulating behavior of materials objectively.

The science team made use of a special effect: some electrical conductors turn into insulators when strongly cooled down. At the same time, their electric state changes, and when the materials warm up again, their electronic properties also change. The scientists now use the speed of this change to distinguish different classes of insulators.

Inconceivably small time scales are applied in this method: For the classification, they use a laser beam camera to produce a film from individual images taken within femtoseconds. For comparison: If you took one picture every femtosecond for a period of one second, you would end up with 1.000.000.000.000.000 single pictures, while a regular film camera takes only 24 images per second. „The electronic changes visible in the film, take about one to 50 femtoseconds for some materials and 100 to 200 femtoseconds for others," Rossnagel explains. In this manner, the scientists can distinguish one insulator class from another.

One of the heavily discussed insulator materials, titanium diselenide (TiSe2), was now precisely classified. On top of the precise classification of TiSe2, the scientists gave the first experimental evidence for a new class of insulators, the so-called excitonic insulators. „We believe that our results may terminate the discussion about titanium diselenide after decades"; says Rossnagel but admits: „Only after several years of cross-checking our results, we will know for sure if our method is as useful as we think now."

The new classification method uses a camera technique presented by the same team of researchers in the journal Nature in March 2011. It is called „femtosecond time-resolved photoelectron spectroscopy with extreme UV radiation." The current study was the first systematic application of the new camera technique to a scientific question. The study was carried out within the Kiel Nano and Surface Science, one out of four major research themes at Kiel University. It was funded on the German side by the German Federal Ministry for Education and Research (BMBF).


Story Source:

The above story is based on materials provided by Christian-Albrechts-Universitaet zu Kiel. Note: Materials may be edited for content and length.


Journal Reference:

  1. S. Hellmann, T. Rohwer, M. Kallδne, K. Hanff, C. Sohrt, A. Stange, A. Carr, M.M. Murnane, H.C. Kapteyn, L. Kipp, M. Bauer, K. Rossnagel. Time-domain classification of charge-density-wave insulators. Nature Communications, 2012; 3: 1069 DOI: 10.1038/ncomms2078

Cite This Page:

Christian-Albrechts-Universitaet zu Kiel. "Burying the hatchet in the laser lab." ScienceDaily. ScienceDaily, 25 September 2012. <www.sciencedaily.com/releases/2012/09/120925091544.htm>.
Christian-Albrechts-Universitaet zu Kiel. (2012, September 25). Burying the hatchet in the laser lab. ScienceDaily. Retrieved October 31, 2014 from www.sciencedaily.com/releases/2012/09/120925091544.htm
Christian-Albrechts-Universitaet zu Kiel. "Burying the hatchet in the laser lab." ScienceDaily. www.sciencedaily.com/releases/2012/09/120925091544.htm (accessed October 31, 2014).

Share This



More Matter & Energy News

Friday, October 31, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

EU, Russia, Ukraine Seal Breakthrough Gas Accord

EU, Russia, Ukraine Seal Breakthrough Gas Accord

AFP (Oct. 31, 2014) — Russia agrees to resume gas deliveries to war-torn Ukraine through the winter in an EU-brokered, multi-billion dollar deal signed by the three parties in Brussels. Duration: 01:10 Video provided by AFP
Powered by NewsLook.com
Relief After “gas War” Is Averted

Relief After “gas War” Is Averted

Reuters - Business Video Online (Oct. 31, 2014) — A gas war between Russia and Ukraine has been averted. But as Hayley Platt reports a deal was only reached after Kiev's western creditors agreed to partly funding the deal. Video provided by Reuters
Powered by NewsLook.com
Jaguar Land Rover Opens $800 Million Factory in Britain

Jaguar Land Rover Opens $800 Million Factory in Britain

AFP (Oct. 30, 2014) — British luxury car manufacturer Jaguar Land Rover opened a $800 million engine manufacturing centre in western England, creating 1,400 jobs. Duration: 00:45 Video provided by AFP
Powered by NewsLook.com
SkyCruiser Concept Claims to Solve Problem With Flying Cars

SkyCruiser Concept Claims to Solve Problem With Flying Cars

Buzz60 (Oct. 30, 2014) — A start-up company called Krossblade says its SkyCruiser concept flying car solves the problem with most flying car concepts. Mara Montalbano (@maramontalbano) explains. Video provided by Buzz60
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:

Strange & Offbeat Stories

 

Space & Time

Matter & Energy

Computers & Math

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins