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"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.'"
This sounds cool, but what they are not telling you is that it will stop working if you bring it south of the equator. :)
"The price good men pay for indifference to public affairs is to be ruled by evil men." ~Plato (427-347 BC)
Is this due to the scale of the device/experiment or is it a limitation in the output that they can get it to generate so far?
...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.
I am the lawn!
Oh, yeah. We know how the spin works. But it works only in the PR side of things.
sed -e 's/Chuck Norris/Rajnikant/g' joke > fact
In THIS house, we obey the laws of thermodynamics. So you create a magnetic field, okay. Great. What's to prevent everything that's metallic in the area from moving around it, inducing current in it, and converting it into useless thermal energy? In other words -- what's preventing the battery from discharging? It might be good for a really high-capacity capacitor, but a battery? Batteries are long term.
#fuckbeta #iamslashdot #dicemustdie
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.
Although the actual device... cannot even light up an LED...
So you're telling me this thing is less powerful than a potato?
... and not all of it from the magnets themselves.
At least for the proof of concept stage, they might want to make a light source that consumes significantly less juice than an LED, and has a greater tolerance for fluctuation.
From Wikipedia:
"LEDs must be supplied with the voltage above the threshold and a current below the rating. This can involve series resistors or current-regulated power supplies." http://en.wikipedia.org/wiki/Led#Disadvantages
Using an LED as an example of what this tiny power souce can't power seems futile at this point.
Readers with subscriptions can see the whole paper.
Dog is my co-pilot.
like taking the batteries out of things, then losing them in the toilet, the cat, the microwave...
I suddenly have an urge to put batteries in a cat...
No sig now
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.
Spintronics is a little too far out of my ken (I was always more of a radiation physicist, where everything comes in nice little packages instead of fields), but if I'm reading the paper correctly, they're saying that they can apply a static magnetic field to one of these devices and then can measure a voltage drop across a resistor hooked up to the device. They can get a few millivolts from a 1.2 Tesla field, which persists for at least ten minutes but does decay in that time frame. When they remove the magnetic field, the voltage disappears.
I guess my question is that if the field is static, where is the energy coming from that drives the current giving rise to the voltage? I'm also wondering how one regenerates the voltage after it discharges completely.
Bypassing the layers of blogs, here's the actual paper. But it costs $32 to read more than the abstract.
This is an application of superparamagnetism. Paramagnetism is ordinarily a weak phenomenon, but there are some new materials for which this effect is much stronger.
It's too early to tell if this is useful. Right now, it's in the category of "minor development in materials science overpromoted as a major breakthrough". It might turn out to have some relevance to MRI imaging or disk drives, both of which rely on fine-scale magnetic effects.