Major Breakthrough In Spintronics Research 106
Invisible Pink Unicorn writes "Spintronics is the field of research into developing devices that rely on electron spin rather than electron charge to carry information. A major advance has been made by the Naval Research Laboratory (NRL), where they have for the first time generated, modulated, and electrically detected a pure spin current in silicon. Progress in this field is expected to lead to devices which provide higher performance with lower power consumption and heat dissipation. Basic research efforts at NRL and elsewhere have shown that spin angular momentum, another fundamental property of the electron, can be used to store and process information in metal and semiconductor based devices. The article abstract is available from Applied Physics Letters."
i see what i did there. (Score:2, Funny)
Yes, I believe it's called a "Phonograph".
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Yes, I believe it's called a "Phonograph".
Spintronics (Score:1, Funny)
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I don't get it (Score:5, Insightful)
Well, fair enough; I can readily imagine that if you could get information to flow through a magical material without having to actually make electrons move, that would be great. No more of that pesky knocking into the lattice that they do which converts their motion into heat.
But...um...how exactly do you get a spin current without the electrons actually moving? I mean, given that the spins in question are nailed to the electron? Seems tricky. Like driving down the highway without having your car move...
Furthermore, if we read further down the abstract, we find this:
"NRL scientists first inject a spin polarized electrical current. . .
Sounds to me like the existence of their spin current depends on the existence of an old-fashioned charge current. So how's this help? How is this a "key enabling advance" (as the press release calls it), still less a "major breakthrough" as the
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I don't see the problem with "blogosphere," by the way -- the extra "o" is just added to make it roll off the tongue easier, and there's plenty of
Re:I don't get it (Score:4, Funny)
At some point you just give it a name and move on.
Although I'd still like to give the person responsible for "blog" a kick in the nuts.
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And I too, want to be next in line after you in giving the person responsible for "blog" a kick in the nuts.
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Based on a quick Google search, I'd say you're probably completely incorrect about any connection to Japanese convention. See example below. And on the off chance that was supposed to be humorous, well, don't quit your day job.
http://drweb.typepad.com/dwdomain/2005/05/what_is_the_or [typepad.com]
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Nice and clear, descriptive, to the point. Don't need to go get the latest jargon dictionary and look up some newfangled buzzword.
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If you throw out the phrase to somebody who doesn't know what it is, then sure, you probably should have explained better, or expect to be asked for an explanation. Spintronics is a convenience. Do you really think that a bunch of researchers, who presumably work on this dail
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My point was that objecting to the "o" in "blogosphere" merely because there was no pre-existing "o" in "blog" or "sphere" is overly pedantic. Do you disagree? Or are you one o
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Re:I don't get it (Score:5, Informative)
Spintronic devices make use of the spin of electrons. Whence, Spintronics.
Re:I don't get it (Score:5, Interesting)
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How do you entangle billions of electrons to the 'reader'?
How will you know which one you 'read'?
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Re:I don't get it (Score:5, Informative)
1. The spin ups will turn to spin downs and cause nearby spin downs to turn spin up.
2. The spin up electrons will move to the right (just picking a random direction), and this will be compensated for by having spin down move left. The result is a net spin current with no net charge current.
To generate this, a spin polarized charge current is generally used. In this paper they used a ferromagnet contact as a source. The setup is basically a 3-way intersection.
Lead 1 is just a floating lead not connected to any ground.
Lead 2 is the ferromagnetic lead
Lead 3 is a ground connection
A voltage is applied between Lead 2 and Lead 3 causing an electrical current to flow. The electrons come out of the ferromagnet partially polarized. This current then goes into the ground Lead 3. All charge current flows from Lead 2 to Lead 3. However, the excess spin up electrons in the junction cause spins to diffuse down the floating Lead 1. No charge current flows down Lead 1 because it has nowhere to go. The result is a net spin current with no net charge current.
Re:I don't get it (Score:5, Interesting)
What's the argument for there being potentially far less dissipative losses with pure spin currents, however? It's still going to interact with the lattice via spin-orbit and spin-spin coupling terms, no? You're still going to get resistive heating, no? Is it just the fact that the magnetic dipole interactions are much shorter range interactions than the Coulomb force? (Except wouldn't it be a screened Coulomb force in the lattice anyway?)
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An interesting way to think about it is that when you have a standard piece of conducting material, it's not that there is no current flowing in it while it sits there not hooked up to a source; actually the electrons go all over the place inside the material. Current flows right to left, left to right, but it all balances out and there is no net current. Resistive heating only occurs when you have net charge current.
As I see it, this is a quite interesting statement, because it mixes the time scales present in the system so thoroughly. It somewhat assumes that the lattice is separate from the electrons, even at equilibrium (that is, when there is no net charge flow). In reality, the charge-carriers interact with the lattice constantly (thus not just jumping off the piece of material willy-nilly when the lattice ends at an edge, for example), and there is uniformity of energy density between the charge carriers and
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No, wait...I don't think this is right. You get plenty of heating from eddy currents, which don't cause a net transport of charge. Plus, it's not true that there is zero charge transport going on in a conductor at equilibrium. There are plenty of thermal fluctuations in the population of electrons near the Fermi surface, and these will give rise to short-lived currents as they relax.
However the trick, as I think someone else commented below,
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Re:I don't get it (Score:5, Informative)
the idea for spintronic devices is to use different device physics utilizing the spin of charge carriers vs just their charge. a common device is a GMR read head on hard drives - developed in '88, widespread now. the next step is to make transistors that use spin - this requires a new class of materials (GMR is a metal/macro structure effect), essentially making non-magnetic materials ferromagnetic is the goal. (personally i use ZnO, not Si, but the idea is similar). if you use a ferromagnetic semiconductor of some kind, then there is better charge transfer to other semiconductors vs a ferro metal to semiconductor... and then what you're looking for is a material that has a long spin polarization lifetime (time before the knocking around flips the spin and all of a sudden you have no polarization). so i *think* that they mean a spin current to be something that is 100% spin polarized (ie all spin up) - which means that if aligned with an applied magnetic field there will be minimal scattering therefor lower resistivity and lower heat/phonon interaction. vs. the case of a partially polarized or random spin up/down distribution where the available states in a material subjected to a field are only open to half of the free carriers (ie only spin up states are available because of the field, so only spin up electrons are efficient carriers). all this is very much so like GMR heads, obviously (well i suppose to me).
i've met the authors at conferences, and i'm sure they're less than thrilled with this being labeled a "major breakthrough" though i'm sure they like a bit of the attention. this is pretty cool and interesting stuff that they've done, but it isn't a breakthrough - just another piece of an extremely large and complex puzzle.
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Re:I don't get it (Score:5, Funny)
Press release (Score:2)
That's odd... I thought press releases were all about spin.
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But...um...how exactly do you get a spin current without the electrons actually moving? I mean, given that the spins in question are nailed to the electron? Seems tricky. Like driving down the highway without having your car move...
All cars in existence cover every road, and any given passenger will stand atop their car dancing. All dancing passengers avoid doing the same dance as any other; that'd be embarrasing. The interference between dancers will reach the destination.
Or, just imagine an infinitely high frequency alternating current.
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Probably what they mean when talking about current is that you need a lower current or they believe that it's possible to optimize the process to increase transmitted information while not increasing current.
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Correct me if I'm wrong, but I thought the whole point was not to prevent electrons from moving but to have more information storage on an electron which means you would need less of them to transmit more data.
Right now the way CPUs work on that level is either on (electron movin
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The same way you get a crowd at a football game to do the wave without anyone moving over a seat.
"NRL scientists first inject a spin polarized electrical current. . . .which generates a pure spin current flowing in the opposite direction. . ."
I can't say for sure, but I think this may be incidental to the experimental setup, and not a fundemental restraint on the spin current. Also, this electrical current might be
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The capacitence of these wires is miniscule because the wires are so small but in a modern computer the signal may be turning on/off billions of times a second so it does add up. If I remember correctly it comes
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so it can stay stationary and the chip can just change the spin to, for example, 1/2 for a 1 and -1/2 for a 0.
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Quite easily, actually. Use some mechanism (magnetic fields in the FA) to force an electron's spin to align to a neighboring one, then align the next one, and so on. You get a spin wave travelling through your medium, but the actual electrons don't move.
Oh man (Score:1, Funny)
Re:Oh man (Score:4, Funny)
On
Off
SpinNotFound
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STFriendlyW (Score:1)
I think the joke has something to do with spin doctoring, but I wouldn't swear to it.
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ergo, there is a large crowd here (Score:1)
HTH/HAND
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IANAPP...B == I am not a particle physicist.. but, (Score:1, Interesting)
we are decades away from being able to implement usefully for any real world application.
Since they are using the angular momentum of electrons to register as a voltage for recognition,
how susceptible to interference is such a system? I would imagine simply shining a flashlight
on such a quantum circuit would affect the resultant output... unless I'm way off.
Any microminds care to shed some light on this?
Re:IANAPP...B == I am not a particle physicist.. b (Score:5, Informative)
First of all, they've measured from 5K up to 80K which is about quarter of room temperature, practically there by solid state physics standards (see the Nature paper). Considering that the effect didn't dwindle by more than half in that range, that's a very good sign that it could be brought up to room temperature. The problem is in getting the electrons "lined up" enough. In the Nature paper they estimate that they see about 30% more spin up than down electrons, but for real applications you'd like to get a lot closer to "100% polarization". I guess that problem might be solvable, but it includes a lot of putting very thin layers of material on single crystal with quite extreme tolerances. Then again, chip fab tolerances are quite extreme already.
In cases like this it's hard to figure out how well stuff will work without actually trying, and that's what this recent paper is about: They've built a transistor-like device with technology similar to that which would be used for mass production and measured a (tiny) effect. Now it's a matter of optimisation, and they might just get there, but it'll be years at least before it's time to start drafting the chip layout.
(*) Hint: If it involves building huge accelerators to crash particles together at pseudo-Big-Bang conditions, it's particle physics. If it involves sticking little pieces of semiconductor into a magnet at 5 Kelvin it's solid state physics. Not that solid state physicists don't use particles, we're all over electrons, phonons, excitons, magnons and many other 'ons that ignorants dismiss as "quasi"particles. Hrmph!
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I think what I resent about it is that I now need to allocate two new slots in my mental lexicon—one for "spintronics" (ok, fine, it's a new concept) and one for "-tron-" (but meaning what, exactly?). If they want a catchy new word, why not just call it something new, like 'flarp', or something more regularly derived, like 'spinics' (still an abomination in classical terms, but far more structurally resonable)?
I wish all these PhD-types would go to school, or something! ;)
Anyone want to simplify how this works? (Score:3, Interesting)
Is it simply a case that in spintronics that the electrons used to carry a current don't actually leave their respective atoms (as they do in AC and DC current), but are just being rotated faster/slower or alternating direction?
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With any luck, this won't be something consumers will have to decipher off the back of a box anytime soon. The name raises more questions than it answers.
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It occured to me that "spin" in this sense isn't constrained to following only linear/planar paths. Instead, you could simply "snake" the rotational force in any direction so long as the bearings along the path remain in physical contact from start to end. For example, take a cube matrix of these ball bearings where you can change the path a specific spin could follow. When the rotational force travels horizontally al
Silicon is the only news here (Score:4, Informative)
Future ahoy! (Score:1, Funny)
Forgive me if I'm being obtuse, (Score:2, Funny)
+pitch -pitch +yaw -yaw +roll -roll
Or, of course, this could be denoted as 0 and 1 instead of + and -. However, doesn't that throw out the current binary model? This'll effectively be base six, instead of base two, won't it?
I dunno - this isn't exactly my field,
Re:Forgive me if I'm being obtuse, (Score:4, Informative)
A single spin 1/2 particle like an electron can be in two states. You can measure the spin along x, y or z direction as you wish, and the answer will always come out to either plus or minus hbar/2. (hbar is the reduced Planck's constant).
It's with this spin like momentum and position: You can't know both at once. If you measure a certain spin along x, the spin in y and z directions will be in a Schrödinger's cat like state: Both + and - at once, but if you measure it you'll only see one. Of course you can choose an axis very close the original x, and you'll be very likely (but not sure) to measure the same general direction.
In sum, the easy thing to do with a spin is to treat it like a single bit, just pic one direction and measure along that. (For computer operation you'd probably like using 10-10000 spins at once to limit the effects of noise, just like transistors aren't quite reliable using a single electron (yet)). If you're into the advanced stuff you can have the spin hold one qubit (google it) and do quantum computation, but the technology in this particular report is likely to stay on the classical side.
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Thanks for the answers though, guys. I appreciate it. I come from a graphics background, so I think in terms of 3D graphics, not advanced semi-theoretical physics...
Query: What is spin? (Score:1)
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Quantum computing is the use of particle properties to produce a powerful third state so instead of 1 and 0 you get 1, 0 and both.
Though they do both require physics at the quantum level it would be confusing to lump it all under the same name when they are very different technologies. (There is a lot of confusion with regard to quantum processors already.)
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I have heard that too. It is not clear to me what the distinction is, other than maybe the idea that "spin" is often visualized as a straight line spinning around its midpoint, so the endpoints of the line are going in a circle, and the angular momentum is easy to see as related to the length of the line; but if the length of
spintronics + Ph.D. = spindoctor? (Score:2, Funny)
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Interesting Article, but not a major breakthrough (Score:1, Insightful)
I'd like to add that the farther along in my science career I've
Spintronics? (Score:1)
You realize of course (Score:1)
Would PhD in this field make you a spin doctor? (Score:1)
Vista's version (Score:2, Funny)
Dizzy (Score:4, Funny)