Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Long-range spin currents induced by heat herald a new era for spintronic applications

09.02.2009
Modern electronics is based on the transport of electrons, generated by a difference in electric voltage. In a bid for faster and smaller electronic devices, researchers have turned to the spin of electrons, or spintronics.

However, sustaining spin currents has proven difficult. Now researchers from the RIKEN Advanced Science Institute in Wako with scientists from Keio University, Yokohoma, and Tohoku University, Sendai, have—for the first time—observed the so-called spin Seebeck effect, which is able to generate pure spin currents across macroscopic distances.

The classic Seebeck effect describes the generation of an electric voltage when the ends of a material are at different temperatures. As such, it is used in thermoelectric devices that convert heat into electricity.

In a similar fashion, as reported by the researchers in Nature1, the spin Seebeck effect reported uses a temperature gradient in a magnetic material to create a flow of electron spins in the absence of any external voltage. As a result, spins of opposite polarization assemble at the two ends of the sample, creating a ‘spin voltage’ caused by the different spin polarizations at both ends. This use of thermal effects in spintronics is novel and unexpected. “The electron spin is usually controlled by magnetic fields, so nobody has thought about a thermoelectric response,” says Wataru Koshibae from the research team.

The discovery of the spin Seebeck effect is enabled by the so-called spin Hall effect. Through interactions between the spin current and the atoms in a metal, electrons of different spin orientations get scattered to opposite ends of the metal, creating an electrical voltage. The spin voltage created by the spin Seebeck effect is then detected by thin platinum sheets placed at both ends of the sample.

Importantly, in this setup the electrons don’t move at all, and only spins travel along the sample. This is markedly different to most other schemes where undesirable parallel electronic currents are unavoidable. In addition, there appears to be no limit to the distances along which spin currents can be sustained. “The spin Seebeck effect occurs in samples almost 1 cm long, much longer than the usual spin current decay lengths of 1 nm,” comments Koshibae.

This first observation of the spin Seebeck effect therefore marks a new era in spintronics and opens the door to novel applications. Long-distance spin current are critical to the realization of spintronic devices, and these results offer the generation of spin currents simply through temperature effects.

Reference

1. Uchida, K., Takahashi, S., Harii, K., Ieda, J., Koshibae, W., Ando, K. Maekawa, S. & Saitoh, E. Observation of the spin Seebeck effect. Nature 455, 778–781 (2008).

The corresponding author for this highlight is based at the RIKEN Theoretical Design Team

Saeko Okada | ResearchSEA
Further information:
http://www.rikenresearch.riken.jp/research/645/
http://www.researchsea.com

More articles from Power and Electrical Engineering:

nachricht Engineers program tiny robots to move, think like insects
15.12.2017 | Cornell University

nachricht Electromagnetic water cloak eliminates drag and wake
12.12.2017 | Duke University

All articles from Power and Electrical Engineering >>>

The most recent press releases about innovation >>>

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

Im Focus: First-of-its-kind chemical oscillator offers new level of molecular control

DNA molecules that follow specific instructions could offer more precise molecular control of synthetic chemical systems, a discovery that opens the door for engineers to create molecular machines with new and complex behaviors.

Researchers have created chemical amplifiers and a chemical oscillator using a systematic method that has the potential to embed sophisticated circuit...

Im Focus: Long-lived storage of a photonic qubit for worldwide teleportation

MPQ scientists achieve long storage times for photonic quantum bits which break the lower bound for direct teleportation in a global quantum network.

Concerning the development of quantum memories for the realization of global quantum networks, scientists of the Quantum Dynamics Division led by Professor...

Im Focus: Electromagnetic water cloak eliminates drag and wake

Detailed calculations show water cloaks are feasible with today's technology

Researchers have developed a water cloaking concept based on electromagnetic forces that could eliminate an object's wake, greatly reducing its drag while...

Im Focus: Scientists channel graphene to understand filtration and ion transport into cells

Tiny pores at a cell's entryway act as miniature bouncers, letting in some electrically charged atoms--ions--but blocking others. Operating as exquisitely sensitive filters, these "ion channels" play a critical role in biological functions such as muscle contraction and the firing of brain cells.

To rapidly transport the right ions through the cell membrane, the tiny channels rely on a complex interplay between the ions and surrounding molecules,...

Im Focus: Towards data storage at the single molecule level

The miniaturization of the current technology of storage media is hindered by fundamental limits of quantum mechanics. A new approach consists in using so-called spin-crossover molecules as the smallest possible storage unit. Similar to normal hard drives, these special molecules can save information via their magnetic state. A research team from Kiel University has now managed to successfully place a new class of spin-crossover molecules onto a surface and to improve the molecule’s storage capacity. The storage density of conventional hard drives could therefore theoretically be increased by more than one hundred fold. The study has been published in the scientific journal Nano Letters.

Over the past few years, the building blocks of storage media have gotten ever smaller. But further miniaturization of the current technology is hindered by...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

See, understand and experience the work of the future

11.12.2017 | Event News

Innovative strategies to tackle parasitic worms

08.12.2017 | Event News

AKL’18: The opportunities and challenges of digitalization in the laser industry

07.12.2017 | Event News

 
Latest News

Engineers program tiny robots to move, think like insects

15.12.2017 | Power and Electrical Engineering

One in 5 materials chemistry papers may be wrong, study suggests

15.12.2017 | Materials Sciences

New antbird species discovered in Peru by LSU ornithologists

15.12.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>