Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Semiconductor physics: Taking control of spin

01.02.2013
Generating and sustaining electrical currents with unique properties for information processing comes closer to reality after a successful theoretical demonstration

Spintronics is a form of signal processing similar to that used in traditional electronics, but it takes advantage of a property of electrons known as spin. Spin is often visualized as an arrow about which the electron rotates, much like a top spinning around its axis. Generating a stream of electrons in which these 'arrows' are all parallel - a so-called spin-polarized current (see image) - is the foundation upon which spintronics is based. Imperfections in a material, however, can easily destroy polarization.


Sustaining a spin-polarized current, in which the spin (depicted as an arrow) of each electron (yellow) is aligned, is integral to advancing spintronic applications



Copyright : 2013 A*STAR Data Storage Institute

Simply applying an oscillating voltage across the device could help to maintain a spin-polarized current even in the presence of impurities, according to theoretical research by Seng Ghee Tan at the A*STAR Data Storage Institute, Singapore, and co©workers

Tan and his colleagues considered a two-dimensional electron gas: a system in which the electrons can move only in one plane. When a spin-polarized current flows through such a material, the spins interact with the electron's motion through an effect known as Rashba spin¨Corbit coupling. This makes the spins start to 'wobble' or precess: at first they point upwards but then point downwards, and this reduces the total spin polarization to zero. "We want to prolong the life span of a spin current in the channel by controlling the strength of the Rashba coupling," says Tan. To this end, he and his team investigated a device, known as a spin-current rectifier, that lets a spin current flow with one particular polarization - upwards only, for example.

The researchers developed a simple mathematical equation that predicts the behavior of the spin current as an alternating voltage is applied across the device. Their model shows that when the frequency of the voltage is zero, the spin polarization goes back and forth as expected. "However, by increasing the frequency, we see an increasingly asymmetrical pattern of oscillation in favor of positive polarization," explains Tan. "We call this a gradual process of rectification."

Their approach can even suppress precessional motion entirely. When the external modulation frequency is much faster than the natural precessional frequency of the spins, known as the Larmor frequency, the spins have no time to change direction so remain pointing upwards. Consequently, the system maintains a spin-polarized current.

Once spin currents can be sustained, spintronics will have all the potential of electronics with the additional advantage of an extra degree of control. The spin-current rectifier investigated by Tan and his co-workers could therefore become a vital component in this future technology.

The A*STAR-affiliated researchers contributing to this research are from the Data Storage Institute
Associated links
http://www.research.a-star.edu.sg/research/6619
Journal information
Ho, C. S., Jalil, M. B. A. & Tan, S. G. Sustainable spin current in the time-dependent Rashba system. Journal of Applied Physics 111, 07C327 (2012).

A*STAR Research | Research asia research news
Further information:
http://www.research.a-star.edu.sg/research/6619
http://www.researchsea.com

More articles from Power and Electrical Engineering:

nachricht Mission possible: This device will self-destruct when heated
22.05.2015 | University of Illinois at Urbana-Champaign

nachricht Gamma ray camera may help with Fukushima decontamination*
21.05.2015 | Waseda 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: Basel Physicists Develop Efficient Method of Signal Transmission from Nanocomponents

Physicists have developed an innovative method that could enable the efficient use of nanocomponents in electronic circuits. To achieve this, they have developed a layout in which a nanocomponent is connected to two electrical conductors, which uncouple the electrical signal in a highly efficient manner. The scientists at the Department of Physics and the Swiss Nanoscience Institute at the University of Basel have published their results in the scientific journal “Nature Communications” together with their colleagues from ETH Zurich.

Electronic components are becoming smaller and smaller. Components measuring just a few nanometers – the size of around ten atoms – are already being produced...

Im Focus: IoT-based Advanced Automobile Parking Navigation System

Development and implementation of an advanced automobile parking navigation platform for parking services

To fulfill the requirements of the industry, PolyU researchers developed the Advanced Automobile Parking Navigation Platform, which includes smart devices,...

Im Focus: First electrical car ferry in the world in operation in Norway now

  • Siemens delivers electric propulsion system and charging stations with lithium-ion batteries charged from hydro power
  • Ferry only uses 150 kilowatt hours (kWh) per route and reduces cost of fuel by 60 percent
  • Milestone on the road to operating emission-free ferries

The world's first electrical car and passenger ferry powered by batteries has entered service in Norway. The ferry only uses 150 kWh per route, which...

Im Focus: Into the ice – RV Polarstern opens the arctic season by setting course for Spitsbergen

On Tuesday, 19 May 2015 the research icebreaker Polarstern will leave its home port in Bremerhaven, setting a course for the Arctic. Led by Dr Ilka Peeken from the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI) a team of 53 researchers from 11 countries will investigate the effects of climate change in the Arctic, from the surface ice floes down to the seafloor.

RV Polarstern will enter the sea-ice zone north of Spitsbergen. Covering two shallow regions on their way to deeper waters, the scientists on board will focus...

Im Focus: Gel filled with nanosponges cleans up MRSA infections

Nanoengineers at the University of California, San Diego developed a gel filled with toxin-absorbing nanosponges that could lead to an effective treatment for skin and wound infections caused by MRSA (methicillin-resistant Staphylococcus aureus), an antibiotic-resistant bacteria. This "nanosponge-hydrogel" minimized the growth of skin lesions on mice infected with MRSA - without the use of antibiotics. The researchers recently published their findings online in Advanced Materials.

To make the nanosponge-hydrogel, the team mixed nanosponges, which are nanoparticles that absorb dangerous toxins produced by MRSA, E. coli and other...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International symposium: trends in spatial analysis and modelling for a more sustainable land use

20.05.2015 | Event News

15th conference of the International Association of Colloid and Interface Scientists

18.05.2015 | Event News

EHFG 2015: Securing health in Europe. Balancing priorities, sharing responsibilities

12.05.2015 | Event News

 
Latest News

Mesoporous Particles for the Development of Drug Delivery System Safe to Human Bodies

22.05.2015 | Materials Sciences

Computing at the Speed of Light

22.05.2015 | Information Technology

Development of Gold Nanoparticles That Control Osteogenic Differentiation of Stem Cells

22.05.2015 | Materials Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>