Featured Research

from universities, journals, and other organizations

Shimmering Ferroelectric Domains

Date:
July 26, 2008
Source:
Forschungszentrum Dresden Rossendorf
Summary:
Ferroelectric materials are named after ferromagnetic ones because they behave in a similar way. The main difference: these materials are not magnetic, but permanently electrically polarized. They have great importance for data storage technology and novel piezoelectric devices. Scientists have now produced microscopic images of ferroelectric domains - tiny regions of a ferroelectric material -, where the electric polarization points into different directions.

False color image of the electric domains on the surface of a bariumtitanate crystal. Image (a) was measured with a wavelength of 17.2 micrometers, image (b) of 16.7 micrometers. The color red means a strong signal. The change of the colors from red to blue is clearly visible.
Credit: Image courtesy of Forschungszentrum Dresden Rossendorf

Ferroelectric materials are named after ferromagnetic ones because they behave in a similar way. The main difference: these materials are not magnetic, but permanently electrically polarized.

Related Articles


They have great importance for data storage technology and novel piezoelectric devices. Dresden scientists were able to produce microscopic images of ferroelectric domains - tiny regions of a ferroelectric material -, where the electric polarization points into different directions.

Dr. Lukas M. Eng and his group at the Technische Universitδt Dresden used the free-electron laser at the Forschungszentrum Dresden-Rossendorf (FZD) to study ferroelectric domains. Ferroelectric materials are special crystals like, e.g. bariumtitanate, where the titanium atoms in the crystal lattice are slightly shifted into one direction. This shift results in a polarization and, therefore, in a permanent electric field.

The ferroelectric domains differ only by the direction of the permanent electric field in the material. The two possible types of domains show either an electric field which is oriented parallel to the surface of the crystal or which points perpendicular to the surface. By applying an external field (e.g. electric voltage) one can reverse the polarity of the domains. Because of these properties ferroelectric materials are widely used in novel technological devices, such as in Ferroelectric Random Access Memory (FRAM or FeRam).

The Dresden scientists aimed at getting as clear an image as possible of the domains in order to understand better how they function, and to specifically manipulate the electric charge of the domains for future devices. The size of a bariumtitanate domain is about one to ten micrometers. Optical methods are dependent on the wavelength of the type of “light” which is applied. The free-electron laser at the FZD emits powerful radiation in a wide range of the infrared and THz region of the electromagnetic spectrum – a region where not many other laser sources exist.

The scientists tuned the laser to a frequency which was in resonance with the atomic motion in the bariumtitanate (near 18 Terahertz). Then they shone the invisible laser beam onto a sharp needle (the tip of an atomic force microscope), moving across the sample surface. Finally they measured the light that was scattered away from the needle. It turns out that this signal contains microscopic information about the sample, in fact with a resolution better than 200 nanometers, which is hundred times smaller than the wavelength of the light.

The domains of the ferroelectric material shimmered in different colors. This is due to the fact that the interaction of the infrared light with the crystal via the tip is different for the two types of domains. The technique itself is called near-field microscopy. The researches were taking advantage of the fact that the two types of domains have their individual resonance frequency. This is the frequency at which the largest amount of infrared light is scattered. In the experiment, areas that appear bright in the image (red in false-color) at a wavelength of 16.7 micrometers, become dark (blue in false color), if the wavelength is tuned to 17.2 micrometers, and vice versa.

The results show the huge potential the free-electron laser has when used for near-field microscopy. The large power and tunability are indispensable for this type of investigations. The group is presently extending its activities thanks to funding by the German Science Foundation (DFG). The scientists of TU Dresden and FZD envision applications for other novel material systems like the so-called multi-ferroics, but also for biomolecules or semiconductor nanostructures (e.g. for wafer inspection).


Story Source:

The above story is based on materials provided by Forschungszentrum Dresden Rossendorf. Note: Materials may be edited for content and length.


Journal Reference:

  1. Kehr et al. Anisotropy Contrast in Phonon-Enhanced Apertureless Near-Field Microscopy Using a Free-Electron Laser. Physical Review Letters, 2008; 100 (25): 256403 DOI: 10.1103/PhysRevLett.100.256403

Cite This Page:

Forschungszentrum Dresden Rossendorf. "Shimmering Ferroelectric Domains." ScienceDaily. ScienceDaily, 26 July 2008. <www.sciencedaily.com/releases/2008/07/080723171551.htm>.
Forschungszentrum Dresden Rossendorf. (2008, July 26). Shimmering Ferroelectric Domains. ScienceDaily. Retrieved December 20, 2014 from www.sciencedaily.com/releases/2008/07/080723171551.htm
Forschungszentrum Dresden Rossendorf. "Shimmering Ferroelectric Domains." ScienceDaily. www.sciencedaily.com/releases/2008/07/080723171551.htm (accessed December 20, 2014).

Share This


More From ScienceDaily



More Matter & Energy News

Saturday, December 20, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Building Google Into Cars

Building Google Into Cars

Reuters - Business Video Online (Dec. 19, 2014) — Google's next Android version could become the standard that'll power your vehicle's entertainment and navigation features, Reuters has learned. Fred Katayama reports. Video provided by Reuters
Powered by NewsLook.com
AP Review: Nikon D750 and GoPro Hero 4

AP Review: Nikon D750 and GoPro Hero 4

AP (Dec. 19, 2014) — What to buy an experienced photographer or video shooter? There is some strong gear on the market from Nikon and GoPro. The AP's Ron Harris takes a closer look. (Dec. 19) Video provided by AP
Powered by NewsLook.com
Double-Amputee Becomes First To Move Two Prosthetic Arms With His Mind

Double-Amputee Becomes First To Move Two Prosthetic Arms With His Mind

Buzz60 (Dec. 19, 2014) — A double-amputee makes history by becoming the first person to wear and operate two prosthetic arms using only his mind. Jen Markham has the story. Video provided by Buzz60
Powered by NewsLook.com
Navy Unveils Robot Fish

Navy Unveils Robot Fish

Reuters - Light News Video Online (Dec. 18, 2014) — The U.S. Navy unveils an underwater device that mimics the movement of a fish. Tara Cleary reports. Video provided by Reuters
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