Curved carbon for electronics of the future

January 23, 2011
An electron has a magnetic field attached -- the so-called spin. One can imagine that all electrons carry around a little bar magnet. In flat graphite layers the small bar magnets point in random directions. By bending the atom thin graphite layer into a tube with a diameter of just a few nanometers the individual electrons are forced to move in simple circles around the tube and all the spins align in the direction of the tube. This feature can be used in future nanoelectronics. Credit: Thomas Sand Jespersen, postdoc, Nanophysics, Niels Bohr Institute, University of Copenhagen

A new scientific discovery could have profound implications for nanoelectronic components. Researchers from the Nano-Science Center at the Niels Bohr Institute, University of Copenhagen, in collaboration with Japanese researchers, have shown how electrons on thin tubes of graphite exhibit a unique interaction between their motion and their attached magnetic field – the so-called spin. The discovery paves the way for unprecedented control over the spin of electrons and may have a big impact on applications for spin-based nanoelectronics. The results have been published in the prestigious journal Nature Physics.

Carbon is a wonderfully versatile element. It is a basic building block in living organisms, one of the most beautiful and hardest materials in the form of diamonds and is found in pencils as graphite. Carbon also has great potential as the foundation for computers of the future as components can be produced from flat, atom thin graphite layers, observed for the first time in the laboratory in 2004 – a discovery which elicited last year's Nobel Prize in Physics.

In addition to a charge all have an attached – a so-called . One can imagine that all electrons carry around a little bar magnet. The electron's spin has great potential as the basis for future computer chips, but this development has been hindered by the fact that the spin has proved difficult to control and measure.

In flat graphite layers the movement of the electrons do not affect the spin and the small bar magnets point in random directions. As a result, graphite was not an obvious candidate for spin based electronics at first.

New spin in curved carbon

"However, our results show that if the layer is curved into a tube with a diameter of just a few nanometers, the spin of the individual electrons are suddenly strongly influenced by the motion of the electrons. When the electrons on the nanotube are further forced to move in simple circles around the tube the result is that all the spins turn in along the direction of the tube", explain the researchers Thomas Sand Jespersen and Kasper Grove-Rasmussen at the Nano-Science Center at the Niels Bohr Institute.

It has previously been assumed that this phenomenon could only happen in special cases of a single electron on a perfect carbon nanotube, floating freely in a vacuum – a situation that is very difficult to realize in reality. Now the researchers' results show that the alignment takes place in general cases with arbitrary numbers of electrons on carbon tubes with defects and impurities, which will always be present in realistic components.

The interaction between motion and spin was measured by sending a current through a nanotube, where the number of electrons can be individually controlled. The two Danish researchers explain that they have further demonstrated how you can control the strength of the effect or even turn it off entirely by choosing the right number of electrons. This opens up a whole range of new possibilities for the control of and application of the spin.

Unique Properties

In other materials, like gold for example, the motion of the electrons also have a strong influence on the direction of the spin, but as the motion is irregular, one cannot achieve control over the spin of the electrons. Carbon distinguishes itself once again from other materials by possessing entirely unique properties – properties that may be important for future nanoelectronics.

Explore further: New STM Microscope To Study Propeties of Electron Spin

More information: Nature Physics paper: DOI:10.1038/NPHYS1880

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12 comments

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Quantum_Conundrum
2.5 / 5 (15) Jan 23, 2011
shhhhh!

Don't tell the mainstream anything. They won't believe you anyway unless you write ten peer reviewed papers, have video evidence from two independent witnesses, and can explain "why".

This is exactly what is always a joke about mainstream. Theory says something can't be done, and then almost nobody ever bothers to test the theory.

Circum navigation
flight
lunar landing
now this

Possibly cold fusion...

What next? Warp Drive?
sorg
3 / 5 (4) Jan 23, 2011
Human beings should not be considered the yardstick of what defines reality.
We are tool makers not reality makers.
Science is a constant ongoing investigation
not the conclusion to what is possible.
Going
4 / 5 (2) Jan 23, 2011
I'd love to see what the electronics of a century from now will be like. My guess is it will be as unrecognisable as today's microchips would have been in the vacuum tube era.
Telekinetic
1.5 / 5 (8) Jan 23, 2011
"What next? Warp Drive?"

If you can imagine it, it will come to pass. Invisibility is around the corner, and anti-gravity is next. I can't wait.
electrodynamic
3 / 5 (1) Jan 23, 2011
Nobody even mentioned quantum computers, but the application is pretty obvious. Of course you could use the electron spins extra possible values without the device being a quantum computer. Another thing that a lot of people seem to be missing. You don't have to store a qbit, or an electron in a certain state, you only have to store the value that state represents, which could be done conventionally.
ormondotvos
4 / 5 (2) Jan 23, 2011
And what if you could align all the spins from a trillion carbon tubes?

Spindizzies. "Cities in Flight"
Telekinetic
1.7 / 5 (6) Jan 23, 2011
Imagination is more important than knowledge. For knowledge is limited, whereas imagination embraces the entire world, stimulating progress, giving birth to evolution. It is, strictly speaking, a real factor in scientific research. - A.E.
Read it and weep, cowards.
trekgeek1
5 / 5 (1) Jan 24, 2011
Imagination is more important than knowledge. For knowledge is limited, whereas imagination embraces the entire world, stimulating progress, giving birth to evolution. It is, strictly speaking, a real factor in scientific research. - A.E.
Read it and weep, cowards.


Imagination is great for determining what could be. Science and the knowledge acquired from it determine what is, completely independent of what we desire. Imagination without knowledge is nothing but a dream. Imagination guided by knowledge leads to advancements in technology and progress in life.
antialias
5 / 5 (1) Jan 24, 2011
Imagination without knowledge ist useless. Knowledge without imagination is useful.

Now you decide which is 'more important'.

The combination of both is what science is all about.
Telekinetic
1 / 5 (4) Jan 24, 2011
Before you spout your unprocessed blather, you ought to know who you're arguing with; A.E.,who we knew as Albert Einstein. Now reread what I posted, and savor his poetic wisdom.
antialias
not rated yet Jan 24, 2011
I am well aware that the quote is by Einstein - however you qoute it out of context. I am pretty sure that Einstein would agree that without his in-depth knowledge of mathematics and physics all his genius/innovation would have lead to nothing. Relativity - though revolutionary - requires some prior knowledge in these fields.

Innovation without knowledge leads to art.
Knowledge without innovation leads to engineering.

With only the former you can do...nothing (except create something that will others cause to go: "Puuurty")
With the latter at least you can do something to help people.

To do science you need to have an aptitude for both (speaking from experience here).
RETT
not rated yet Feb 07, 2011
Let us all bow down to the great god A.E. That is the same A.E. That is the same A.E., who spent most of his time from the 20's on trying to disprove the quantum theory that he helped give birth to. A good deal of quantum theory was not and likely could not have been imagined. It had to be discovered, by experiment and by derivation. It was the derivations of quantum theory that predicted a great deal of the basis of modern electronics and physics. Nobody would believe many of the predicted effectsw until they were actually observed. And quantum theory itself derived from conflicting observations. Imagination had little or nothing to do with it. Imagination may give you ideas to test, but it requires present knowledge to do the testing. Science is not lacking in imaginative ideas to test, but means to test even a small part of those ideas. No matter how wonderful an idea, it is current knowledge that gives us the ability to test, prove, and then build.

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