Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

A Fresh Spin in Quantum Physics: The ‘Spin Triplet’ Supercurrent

17.02.2006


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.

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.

Wendy Lawton | EurekAlert!
Further information:
http://www.brown.edu

More articles from Physics and Astronomy:

nachricht One-way roads for spin currents
23.05.2018 | Singapore University of Technology and Design

nachricht Tunable diamond string may hold key to quantum memory
23.05.2018 | Harvard John A. Paulson School of Engineering and Applied Sciences

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

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

Im Focus: LZH showcases laser material processing of tomorrow at the LASYS 2018

At the LASYS 2018, from June 5th to 7th, the Laser Zentrum Hannover e.V. (LZH) will be showcasing processes for the laser material processing of tomorrow in hall 4 at stand 4E75. With blown bomb shells the LZH will present first results of a research project on civil security.

At this year's LASYS, the LZH will exhibit light-based processes such as cutting, welding, ablation and structuring as well as additive manufacturing for...

Im Focus: Self-illuminating pixels for a new display generation

There are videos on the internet that can make one marvel at technology. For example, a smartphone is casually bent around the arm or a thin-film display is rolled in all directions and with almost every diameter. From the user's point of view, this looks fantastic. From a professional point of view, however, the question arises: Is that already possible?

At Display Week 2018, scientists from the Fraunhofer Institute for Applied Polymer Research IAP will be demonstrating today’s technological possibilities and...

Im Focus: Explanation for puzzling quantum oscillations has been found

So-called quantum many-body scars allow quantum systems to stay out of equilibrium much longer, explaining experiment | Study published in Nature Physics

Recently, researchers from Harvard and MIT succeeded in trapping a record 53 atoms and individually controlling their quantum state, realizing what is called a...

Im Focus: Dozens of binaries from Milky Way's globular clusters could be detectable by LISA

Next-generation gravitational wave detector in space will complement LIGO on Earth

The historic first detection of gravitational waves from colliding black holes far outside our galaxy opened a new window to understanding the universe. A...

Im Focus: Entangled atoms shine in unison

A team led by Austrian experimental physicist Rainer Blatt has succeeded in characterizing the quantum entanglement of two spatially separated atoms by observing their light emission. This fundamental demonstration could lead to the development of highly sensitive optical gradiometers for the precise measurement of the gravitational field or the earth's magnetic field.

The age of quantum technology has long been heralded. Decades of research into the quantum world have led to the development of methods that make it possible...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Save the date: Forum European Neuroscience – 07-11 July 2018 in Berlin, Germany

02.05.2018 | Event News

Invitation to the upcoming "Current Topics in Bioinformatics: Big Data in Genomics and Medicine"

13.04.2018 | Event News

Unique scope of UV LED technologies and applications presented in Berlin: ICULTA-2018

12.04.2018 | Event News

 
Latest News

Research reveals how order first appears in liquid crystals

23.05.2018 | Life Sciences

Space-like gravity weakens biochemical signals in muscle formation

23.05.2018 | Life Sciences

NIST puts the optical microscope under the microscope to achieve atomic accuracy

23.05.2018 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>