Featured Research

from universities, journals, and other organizations

A Fresh Spin In Quantum Physics: The 'Spin Triplet' Supercurrent

Date:
February 20, 2006
Source:
Brown University
Summary:
For the first time, scientists have created a "spin triplet" supercurrent through a ferromagnet over a long distance. Achieved with a magnet developed at Brown University and the University of Alabama, the feat upends long-standing theories of quantum physics -- and may be a boon to the budding field of "spintronics," where the spin of electrons, along with their charge, is harnessed to power computer chips and circuits. Results are published in Nature.

Superconductivity occurs when electrical current moves without resistance, a phenomenon that gave rise to particle accelerators, magnetic resonance imagining machines and trains that float, friction-free, on their tracks.

Related Articles


Under quantum physics theory, conventional superconductivity is not supposed to occur in ferromagnets. When electrons pass through these crystalline materials, they realign in ways that won’t allow resistance-free conductivity. While supercurrent through a ferromagnet has been observed, it moved only an extremely short distance before resistance kicked in.

But a team of scientists from Delft University of Technology, Brown University and the University of Alabama has now accomplished this physics feat, creating a “spin triplet” supercurrent through a unique ferromagnet.

As explained in the current issue of Nature, the team’s experimental system converts the spin, or rotation, of pairs of electrons in such a way that suggests they exist in three quantum states inside the new magnet. There’s the standard “spin up” and “spin down” – a reference to an electron’s angular momentum – but also a middle state. Picture a planet that was thought to rotate two ways: With its North Pole pointing up or pointing down. But now it’s found that this planet can be made to rotate on its side, with its North Pole pointing out in a 90-degree angle.

While such a “spin triplet” conversion in a ferromagnet was predicted in theory, the team offers the first experimental evidence for the phenomenon.

The team also showed that this current travels a comparatively long distance. In previous experiments, current passed through a ferromagnet sandwiched between superconductors spaced one nanometer apart. Under the new system, the space between superconductors was 300 nanometers apart.

“It’s a beautiful thing,” said Gang Xiao, a Brown professor of physics. “What we’ve done was considered almost impossible. But physicists never take ‘no’ for an answer.”

Xiao spent eight years perfecting the ferromagnet with Brown graduate students and colleagues from the University of Alabama. The magnet is black, about the size of a postage stamp, and measures only 1,000 atoms thick. To make it, chromium oxide was heated until it vaporized. That vapor was transported onto a titanium oxide film, so that only a single crystal layer coated the titanium material.

The magnet was sent to scientists at Delft University of Technology in the Netherlands. A team there placed dozens of tiny superconducting electrodes on top of the magnet then used an electron beam to cut the electrodes, creating the 300-nanometer gap between them. Scientists then tested the system to measure the flow of current.

Xiao hopes that the new ferromagnet can help create technologies in the hot new field of “spintronics,” short for spin-based electronics. While conventional electronics tap the charge of an electron to conduct current, spintronic devices use the spin as well as the charge. The promise: smaller, faster and cheaper computer memory storage and processing.

Already, spintronic technology can be found in computer hard drives. A magnetic version of a random access memory device and a spin-based transistor are under development. So are “quantum computers,” which can perform hyperfast calculations.

Xiao said the spin triplet current created with the ferromagnet would allow for new control in spintronics development.

“Once you understand this new behavior of electrons, you can apply the knowledge in new ways to commercial products,” he said. “The consequences can be significant.”

The Nederlandse Organisatie voor Wetenschappelijk Onderzoek and the National Science Foundation funded the work.


Story Source:

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


Cite This Page:

Brown University. "A Fresh Spin In Quantum Physics: The 'Spin Triplet' Supercurrent." ScienceDaily. ScienceDaily, 20 February 2006. <www.sciencedaily.com/releases/2006/02/060220104142.htm>.
Brown University. (2006, February 20). A Fresh Spin In Quantum Physics: The 'Spin Triplet' Supercurrent. ScienceDaily. Retrieved December 19, 2014 from www.sciencedaily.com/releases/2006/02/060220104142.htm
Brown University. "A Fresh Spin In Quantum Physics: The 'Spin Triplet' Supercurrent." ScienceDaily. www.sciencedaily.com/releases/2006/02/060220104142.htm (accessed December 19, 2014).

Share This


More From ScienceDaily



More Matter & Energy News

Friday, December 19, 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
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
3D Printed Cookies Just in Time for Christmas

3D Printed Cookies Just in Time for Christmas

Reuters - Innovations Video Online (Dec. 18, 2014) A tech company in Spain have combined technology with cuisine to develop the 'Foodini', a 3D printer designed to print the perfect cookie for Santa. Ben Gruber 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