Important progress for spintronics: A spin amplifier to be used in room temperature

November 16, 2012
A schematic picture of the defect-engineered spin amplifier demonstrated in this work. The wave pattern symbolizes the time variation of the spin signal, namely the difference between the numbers of spin-up and spin-down electrons. The red and blue arrows represent the period with more spin-up and spin-down electrons, respectively. The amplitude of the wave reflects the strength of the spin signal, which is weak before entering the spin amplifier but becomes stronger when exiting. The defects that have enabled the spin-amplification functionality of a non-magnetic semiconductor are indicated by the yellow balls, each with a spin-polarized localized electron (indicated by the red and blue arrows). The spin direction of this localized electron rapidly follows the sign of the input spin signal, which serves to only attract and remove the incoming electrons with an undesired spin orientation. This leads to a significant enhancement in the spin polarization of the electrons passing the spin amplifier, giving rise to a strongly amplified output spin signal that has truthfully cloned the exactly same time-varying function and thus the spin-encoded information of the input spin signal. Credit: Weimin Chen/Adv. Mater. 2012, DOI 10.1002/adma.20120597

A fundamental cornerstone for spintronics that has been missing up until now has been constructed by a team of physicists at Linköping University in Sweden. It's the world's first spin amplifier that can be used at room temperature.

Great hopes have been placed on as the next big in the field of electronics. Spintronics combines microelectronics, which is built on the charge of , with the magnetism that originates in the electrons' spin. This lays the foundation for entirely new applications that fire the imagination. The word "spin" aims at describing how electrons spin around, much like how the Earth spins on its own axis.

But turning theory into practice requires amplifying these very weak signals. Instead of transistors, rectifiers, and so on, the building blocks of spintronics will be formed by things like spin filters, spin amplifiers, and spin detectors. Through regulating and controlling electron spin, it will be possible to store data more densely and process it many times faster – and with greater – than today's technology.

In 2009, an LiU group from the Department of Functional Electronic Material, led by Professor Weimin Chen, presented a new type of spin filter that works at room temperature. The filter lets through electrons that have the desired spin direction, screening out the others. This function is crucial for constructing new types of components such as spin diodes and spin lasers.

Now the same group, in collaboration with colleagues from Germany and the United States, has published an article in the highly-ranked journal , where they present an effective spin amplifier based on a non-magnetic semiconductor. The amplification occurs through deliberate defects in the form of extra gallium atoms introduced into an alloy of , , nitrogen and arsenic.

A component of this kind can be set anywhere along a path of spin transport to amplify signals that have weakened along the way. By combining this with a spin detector, it may be possible to read even extremely weak spin signals.

"It's an advance that blazes a trail for a solution to the problem of controlling and detecting electron spin at room temperature, which is a prerequisite for the breakthrough of spintronics," says Weimin Chen.

Explore further: Spin-polarized electrons on demand

More information: Room-temperature electron spin amplifier based on Ga(In)NAs alloys by Y. Puttisong, I.A. Buyanova, A.J. Ptak, C.W. Tu, L. Geelhaar, H. Richert and W.M. Chen. Advanced Materials online 26 October 2012. DOI 10.1002/adma.20120597

Related Stories

Spin-polarized electrons on demand

January 21, 2009

Many hopes are pinned on spintronics. In the future it could replace electronics, which in the race to produce increasingly rapid computer components, must at sometime reach its limits. Different from electronics, where whole ...

Spin polarization achieved in room temperature silicon

November 27, 2009

( -- A group in The Netherlands has achieved a first: injection of spin-polarized electrons in silicon at room temperature. This has previously been observed only at extremely low temperatures, and the achievement ...

Spin polarized supercurrents optimized with a simple flip

May 14, 2012

( -- Researchers from Michigan State University, the NIST Center for Neutron Research, and the NIST Center for Nanoscale Science and Technology have discovered the key to controlling and enhancing the lossless flow ...

A step forward for ultrafast spintronics

September 6, 2012

(—In spin based electronics the spin of the electron is used as a carrier of information. To meet the need for faster electronics, the speed must be increased as far as possible. Today, Uppsala physicists show ...

A new probe for spintronics

September 12, 2012

The spin Hall effect (SHE) enables us to create spin current in  non-magnetic materials without using ferromagnetic materials. It is a crucial element in the central idea behind spintronics, that of manipulating currents ...

Recommended for you

Fusion reactors 'economically viable' say experts

October 2, 2015

Fusion reactors could become an economically viable means of generating electricity within a few decades, and policy makers should start planning to build them as a replacement for conventional nuclear power stations, according ...

Iron-gallium alloy shows promise as a power-generation device

September 29, 2015

An alloy first made nearly two decades ago by the U. S. Navy could provide an efficient new way to produce electricity. The material, dubbed Galfenol, consists of iron doped with the metal gallium. In new experiments, researchers ...

Extending a battery's lifetime with heat

October 1, 2015

Don't go sticking your electronic devices in a toaster oven just yet, but for a longer-lasting battery, you might someday heat them up when not in use. Over time, the electrodes inside a rechargeable battery cell can grow ...

Invisibility cloak might enhance efficiency of solar cells

September 30, 2015

Success of the energy turnaround will depend decisively on the extended use of renewable energy sources. However, their efficiency partly is much smaller than that of conventional energy sources. The efficiency of commercially ...


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.