Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Transporting spin: A graphene and boron nitride heterostructure creates large spin signals

16.08.2017

Graphene Flagship scientists based at the University of Groningen, The Netherlands, have created a device based on a blilayer of graphene and boron nitride which shows unprecedented spin transport efficiency at room temperature. Highlighting the potential of creating devices containing graphene and related materials, the spin signal measured here is so large that it can be used in real life applications such as spin based logic and transistors.

Published in Nature Communications this research, led by Professor Bart van Wees, University of Groningen, The Netherlands, reports a graphene-based device in which electron spins can be injected and detected at room temperature with high efficiency. The key here is the interplay between the graphene and the boron nitride in the way that they conduct electron spins.


A layer-by-layer schematic alongside an optical microscopic picture of a graphene and boron nitride heterostructure device which shows unprecedented spin transport efficiency at room temperature.

Credit: M. Gurram, S. Omar and B.J. van Wees, University of Groningen

Spin can be thought of as the rotation of an electron around its own axis. It is a form of intrinsic angular momentum and can be detected as a magnetic field with one of two orientations: up and down. Electron spin is difficult to handle and often loses direction over time. To use electron spin in a device, spin polarisation is important -- this is the ability to control the fraction of electrons with a spin up or down. 'Spin polarization can be achieved by sending the electrons through a ferromagnetic material', van Wees explains.

Professor van Wees and his team showed that they could greatly improve the efficiency of the injection and detection of spin electrons into graphene by using the insulator boron nitride in between the graphene layer and the ferromagnetic spin injector/detector electrodes.

'Graphene is a very good material for spin transport, but it does not allow one to manipulate the spins', says van Wees 'To inject spins into the graphene, one has to make them pass from a ferromagnet through a boron nitride insulator by quantum tunnelling. We found that using a two-atom layer of boron nitride resulted in a very strong spin polarization of up to 70 percent, ten times what we usually get.'

In the devices produced the polarisation increased with voltage, challenging the current thinking that it is only the ferromagnetic that polarises spin. Instead it would seem that it is the quantum tunnelling that polarises the spin in his devices. The researchers also found a similar tenfold increase in spin detection in the same device. 'So overall, the signal increased by a factor of 100.' said van Wees.

This creates many possibilities. 'We can now inject spins into graphene and measure them easily after they travel some distance. One application would be as a detector for magnetic fields, which will affect the spin signal.' Another possibility would be to build a spin logic gate or a spin transistor. As the experiments with the new device were conducted at room temperature such applications are quite close. 'However', van Wees warns, 'we used graphene which we obtained by exfoliation, using Scotch tape to peel monolayers off a piece of graphite. This is not suitable for large scale production.' Techniques to make high quality graphene on an industrial scale are a focus within the Graphene Flagship with the Work Package Production dedicated to this task.

Speaking about this research is Professor Vladimir Falko, Leader of Enabling Science and Materials Division of the Graphene Flagship: 'Encapsulation of graphene in boron nitride and the use of heterostructures of these two materials for new devices, including tunnelling transistors, is a promising trend in graphene research that has previously delivered many interesting results. The reported observation takes graphene spintronics to the qualitatively new level.'

Spintronics is one of the work packages in the Graphene Flagship where Professor van Wees is the leader. It focuses on investigating room temperature graphene spintronic devices, joining together theoretical and experimental research and is seen as a long term investment for the Graphene Flagship. With so much progress being made on the individual elements that are needed to produce fully functional spintronic devices by the Graphene Flagship's spintronics researchers, the next step is joining these together. The recently published work of Graphene Flagship Partner Professor Saroj Dash of Chalmers University, Sweden, showed the ability to control the amount of spin with a gate voltage - all at room temperature. Facilitating the collaboration on projects such as these is a central aim of the Graphene Flagship.

Professor Andrea Ferrari, Chair of the Management Panel and Science and Technology Officer of the Graphene Flagship added: 'Spintronics has been one of the fundamental work packages since the start of the Flagship. It was always seen as a long term investment. It is exciting to see that so much progress has been made towards devices".

Professor Stephan Roche, Spintronics Work Package Deputy Leader commented further: 'This experimental breakthrough evidences that the Spintronics work package is acting as a pathfinder to bring all the potential of graphene and related materials to future practical applications in spintronics. It is however also clear that more efforts and investment are crucially needed to accelerate large scale integration of such type of realizations into the European fab environment for acquiring industrial leadership beyond the recognised European scientific excellence in this field.'

Media Contact

Sian Fogden
comms@graphene.cam.ac.uk
44-122-376-2418

 @GrapheneCA

http://graphene-flagship.eu 

Sian Fogden | EurekAlert!

More articles from Materials Sciences:

nachricht Less is more to produce top-notch 2D materials
20.11.2017 | The Agency for Science, Technology and Research (A*STAR)

nachricht The stacked colour sensor
16.11.2017 | Empa - Eidgenössische Materialprüfungs- und Forschungsanstalt

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: A “cosmic snake” reveals the structure of remote galaxies

The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.

Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...

Im Focus: Visual intelligence is not the same as IQ

Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.

That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...

Im Focus: Novel Nano-CT device creates high-resolution 3D-X-rays of tiny velvet worm legs

Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.

During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....

Im Focus: Researchers Develop Data Bus for Quantum Computer

The quantum world is fragile; error correction codes are needed to protect the information stored in a quantum object from the deteriorating effects of noise. Quantum physicists in Innsbruck have developed a protocol to pass quantum information between differently encoded building blocks of a future quantum computer, such as processors and memories. Scientists may use this protocol in the future to build a data bus for quantum computers. The researchers have published their work in the journal Nature Communications.

Future quantum computers will be able to solve problems where conventional computers fail today. We are still far away from any large-scale implementation,...

Im Focus: Wrinkles give heat a jolt in pillared graphene

Rice University researchers test 3-D carbon nanostructures' thermal transport abilities

Pillared graphene would transfer heat better if the theoretical material had a few asymmetric junctions that caused wrinkles, according to Rice University...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Ecology Across Borders: International conference brings together 1,500 ecologists

15.11.2017 | Event News

Road into laboratory: Users discuss biaxial fatigue-testing for car and truck wheel

15.11.2017 | Event News

#Berlin5GWeek: The right network for Industry 4.0

30.10.2017 | Event News

 
Latest News

Antarctic landscape insights keep ice loss forecasts on the radar

20.11.2017 | Earth Sciences

Filling the gap: High-latitude volcanic eruptions also have global impact

20.11.2017 | Earth Sciences

Water world

20.11.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>