Featured Research

from universities, journals, and other organizations

Mechanism To Increase Magnetic Response Of Ferromagnetic Semiconductor Identified

Date:
March 11, 2009
Source:
DOE/Argonne National Laboratory
Summary:
When squeezed, electrons increase their ability to move around. In compounds such as semiconductors and electrical insulators, such squeezing can dramatically change the electrical- and magnetic- properties. Now scientists have manipulated electron mobility and pinpointed the mechanism controlling the strength of magnetic interactions -- and hence the material's magnetic ordering temperature.

A ferromagnetic-semiconductor Europium oxide sample is subjected to high pressures in a diamond anvil cell. The electronic structure is simultaneously probed with circularly-polarized x-rays at the Advanced Photon Source, revealing the mechanism responsible for the strengthening of magnetic interactions under pressure.
Credit: Image courtesy of DOE/Argonne National Laboratory

When squeezed, electrons increase their ability to move around. In compounds such as semiconductors and electrical insulators, such squeezing can dramatically change the electrical- and magnetic- properties.

Related Articles


Under ambient pressure, Europium oxide becomes ferromagnetic only below 69 Kelvin, limiting its applications. However, its magnetic ordering temperature is known to increase with pressure, reaching 200 Kelvin when squeezed by 150,000 atmospheres. The relevant changes in electronic structure responsible for such dramatic changes, however, remained elusive.

Now scientists at the U.S. Department of Energy's Argonne National Laboratory have manipulated electron mobility and pinpointed the mechanism controlling the strength of magnetic interactions- and hence the material's magnetic ordering temperature.

"EuO is a ferromagnetic semiconductor and is a material that can carry spin polarized currents, which is an integral element of future devices aimed at manipulating both the spin and the charge of electrons in new generation microelectronics," Argonne's Postdoctoral researcher Narcizo Souza-Neto said.

Using powerful X-rays from the Advanced Photon Source to probe the material's electronic structure under pressure, Souza-Neto and Argonne Physicist Daniel Haskel report in the February 6 issue of Physical Review Letters that localized, 100 percent polarized Eu 4f electrons become mobile under pressure by hybridizing with neighboring, extended electronic states. The increased mobility enhances the indirect magnetic coupling between Eu spins resulting in a three-fold increase in the ordering temperature.

While the need for large applied pressures may seem a burden for applications, large compressive strains can be generated at interfacial regions in EuO films by varying the mismatch in lattice parameter with selected substrates. By pinpointing the mechanism the research provides a road map for manipulating the ordering temperatures in this and related materials, e.g., through strain or chemical substitutions with the ultimate goal of reaching 300 Kelvin (room temperature).

"Manipulation of strain adds a new dimension to the design of novel devices based on injection, transport, and detection of high spin-polarized currents in magnetic/semiconductor hybrid structures", Haskel said.

Other authors in the paper are graduate student Yuan-Chieh Tseng (Northwestern U.) and Gerard Lapertot (CEA-Grenoble).

Funding for this research was provided by the U.S. Department of Energy's Office of Science.


Story Source:

The above story is based on materials provided by DOE/Argonne National Laboratory. Note: Materials may be edited for content and length.


Cite This Page:

DOE/Argonne National Laboratory. "Mechanism To Increase Magnetic Response Of Ferromagnetic Semiconductor Identified." ScienceDaily. ScienceDaily, 11 March 2009. <www.sciencedaily.com/releases/2009/02/090225132555.htm>.
DOE/Argonne National Laboratory. (2009, March 11). Mechanism To Increase Magnetic Response Of Ferromagnetic Semiconductor Identified. ScienceDaily. Retrieved April 18, 2015 from www.sciencedaily.com/releases/2009/02/090225132555.htm
DOE/Argonne National Laboratory. "Mechanism To Increase Magnetic Response Of Ferromagnetic Semiconductor Identified." ScienceDaily. www.sciencedaily.com/releases/2009/02/090225132555.htm (accessed April 18, 2015).

Share This


More From ScienceDaily



More Computers & Math News

Saturday, April 18, 2015

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

WikiLeaks Refuses To Let Sony Hack Die, Posts Database

WikiLeaks Refuses To Let Sony Hack Die, Posts Database

Newsy (Apr. 17, 2015) WikiLeaks&apos; Julian Assange says the hacked emails and documents "belong in the public domain." Video provided by Newsy
Powered by NewsLook.com
Scientists Create Self-Powering Camera

Scientists Create Self-Powering Camera

Reuters - Innovations Video Online (Apr. 17, 2015) American scientists build a self-powering camera that captures images without using an external power source, allowing it to operate indefinitely in a well-lit environment. Elly Park reports. Video provided by Reuters
Powered by NewsLook.com
The State Of Virtual Reality

The State Of Virtual Reality

Newsy (Apr. 17, 2015) Virtual Reality is still a young industry. What’s on offer and what should we expect from our immersive new future? Video provided by Newsy
Powered by NewsLook.com
Cybercrime Could Cost $400 Bln

Cybercrime Could Cost $400 Bln

Reuters - Business Video Online (Apr. 16, 2015) Representatives from around 160 countries gather at the Hague to discuss cyber space and cyber security, including the dilemmas and challenges regarding the evolution of the internet. Ciara Lee 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