"Spin Battery" Effect Discovered

An anonymous reader writes "Researchers at the University of Miami and at the Universities of Tokyo and Tohoku, in Japan, have discovered a spin battery effect: the ability to store energy into the magnetic spin of a material and to later extract that energy as electricity, without a chemical reaction. The researchers have built an actual device to demonstrate the effect that has a diameter about that of a human hair. This is a potentially game-changing discovery that could affect battery and other technologies. Quoting: Although the actual device... cannot even light up an LED..., the energy that might be stored in this way could potentially run a car for miles. The possibilities are endless, Barnes said.'"

Comments

Cool.

[B5_geek]

This sounds cool, but what they are not telling you is that it will stop working if you bring it south of the equator. :)

Miles?

[noundi]

...the energy that might be stored in this way could potentially run a car for miles. The possibilities are endless, Barnes said.

Awesome, I have yet to travel miles by car.

Re:Miles?

[quickOnTheUptake]

Although the actual device... cannot even light up an LED..., the energy that might be stored in this way could potentially run a car for miles.

This is one of the least informative lines ever included in a tech summary.
Any energy storing tech that's worth it's salt can potentially run a car for miles. It's a question of efficiency and cost. I can potentially power a car for miles with twisted up rubberbands if I want to, but that isn't a breakthrough in the field.
And of course "miles" tells nothing. Powering a car 3-5 miles is next to worthless. If they said 10's of miles we would know this had the potential to replace current tech or at least come close. If they said 100's of miles we would be facing a revolutionary improvement.

Re:Miles?

[Mister Whirly]

"I can potentially power a car for miles with twisted up rubberbands"

So you bought a Yugo too, eh?

Re:Miles?

[MightyYar]

I can potentially power a car for miles with twisted up rubberbands if I want to

I think there is some stimulus money available for you.

CAUTION

[Waffle Iron]

Do not open or crush battery. Severe risk of releasing a life-sucking vortex.

Do not dispose in fire. Doing so could loose a storm of flaming vortices.

Do not use this battery on carnival rides, while figure skating, or place in spinning clothes washer. Risk of severe gyroscopic reactions, which may lead to property damage, personal injury or death.

Re:CAUTION

[dazedNconfuzed]

Do not taunt Magnetic Spin Battery.

Yeah, but..

[AndrewNeo]

Although the actual device... cannot even light up an LED...

So you're telling me this thing is less powerful than a potato?

Re:Achem

[Anonymous Coward]

Yeah you're right. I bet they totally never thought of that.

When did "In THIS house, we obey the laws of thermodynamics" turn into some goddamn meme that gets pulled out when what you really mean is "I don't understand, can anyone please explain?"

Because you're implying that these researchers are in some other house that doesn't obey the laws of physics, and that pointing this out is some revelation. Physicists from three institutions in two countries worked on this - are you really so stupid to think they don't know about thermodynamics? Really?

The Nature pre-publication link

[Scareduck]

Here's the pre-publication link in Nature .

The electromotive force (e.m.f.) predicted by Faraday's law reflects the forces acting on the charge, â"e, of an electron moving through a device or circuit, and is proportional to the time derivative of the magnetic field. This conventional e.m.f. is usually absent for stationary circuits and static magnetic fields. There are also forces that act on the spin of an electron; it has been recently predicted that, for circuits that are in part composed of ferromagnetic materials, there arises an e.m.f. of spin origin even for a static magnetic field. This e.m.f. can be attributed to a time-varying magnetization of the host material, such as the motion of magnetic domains in a static magnetic field, and reflects the conversion of magnetic to electrical energy. Here we show that such an e.m.f. can indeed be induced by a static magnetic field in magnetic tunnel junctions containing zinc-blende-structured MnAs quantum nanomagnets. The observed e.m.f. operates on a timescale of approximately 10^2-10^3 seconds and results from the conversion of the magnetic energy of the superparamagnetic MnAs nanomagnets into electrical energy when these magnets undergo magnetic quantum tunnelling. As a consequence, a huge magnetoresistance of up to 100,000 per cent is observed for certain bias voltages. Our results strongly support the contention that, in magnetic nanostructures, Faraday's law of induction must be generalized to account for forces of purely spin origin. The huge magnetoresistance and e.m.f. may find potential applications in high sensitivity magnetic sensors, as well as in new active devices such as 'spin batteries'.

Readers with subscriptions can see the whole paper.

You 'flywheel' people do realize..

[MoellerPlesset2]

That we're talking about _spin_ here, as in a property of subatomic particles corresponding to an 'intrinsic' angular momentum, not as in something that's physically 'spinning'. Electrons spin +1/2 or -1/2 and that's it. They can't stop. The energy here is being stored in the form of the _orientations_ of these spins, not the spin itself. What's keeping them that way is conservation of spin. Which is analogous to conservation of angular momentum. (Bound) Electrons can't change their spin state spontaneously. Which is why stuff which is magnetized stays that way for a long time. It's also the reason for phosphorescence. While I think what they've done here is undeniably pretty cool, in turning spin-state transitions into electricity directly, it's probably not going to create any real competition for conventional batteries, for fairly simple reasons. Batteries store electricity in the form of chemical redox states, which means adding/removing electrons from atoms/ions. The energy differences between spin states are typically an order of magnitude smaller than the energy difference between redox states.