Nanotechnology + Superconductivity = Spintronics 88
karvind writes "Spintronics is a nanoscale technology in which information is carried not by the electron's charge, as it is in conventional microchips, but by the electron's intrinsic spin and if a reliable way can be found to control and manipulate the spins spintronic devices could offer higher data processing speeds, lower electric consumption, and many other advantages over conventional chips--including, perhaps, the ability to carry out radically new quantum computations. PhysOrg is reporting that University of Notre Dame physicist Boldizsar Janko and his colleagues have found a way to achieve this control using a magnetic semiconductor, insulator and superconducting material stack of thicknesses of order of few dozen nanometers. IBM and Stanford are also looking into spintronics."
Re:Need Wikipedia Update? (Score:3, Insightful)
The wikipedia article is probably referring to the specific ability to make a selective filter to pass/block currents of only a specific spin type. Or to make a transistor to amplify/switch only on a specific spin type. etc.
Is it too late? (Score:3, Insightful)
Is it too late to stop the proliferation of "-tron" words? "-tron" means nothing; "electrons" are so called because of the Greek word for amber, which the Greeks knew to be capable of producing a static charge. What if people abstracted part of that word out and started calling every new technology "something-ber"?
I think the technical name for the combining from "-tron" is a "cranberry morpheme," from "*cran," which apparently has no independent meaning.
Re:boundless optimism (Score:3, Insightful)
Re:DIY? (Score:3, Insightful)
Free electrons means without any other interactions, and spin up and spin down have no preference. In fact, the directions up/down don't mean anything unless some non-isotropic disturbance is present in the system. This would usually be the applied magnetic field.
If you have a ferromagnet, the electrons want to align parallel, so flipping one electron costs energy. This energy can come from thermal excitations, so to get the fully aligned state you need to cool the system down to minimize these excitations.
As for your battery, remember you are fundamentally storing chemical potential to drive current (actually, I'm kind of BSing here, so maybe a chemist can correct this), so aligning the spins probably won't do much. In fact, you'd most likely waste 100x or more of the energy the battery would provide just running the fridges necessary to align the spins.
But like I said, you'd really need a spintronic battery, which maybe some scientists are studying somewhere. A standard battery would lose the spin coherence relativly quickly, even if you charged it with a fully spin-polarized current.
Now about your question, if you put the spins all in spin-down state and put an up-pointing magnetic field, that's alot of energy stored there (assuming no other interactions between the spins that would allow this). But that would be very difficult to set up a state like this.
Actually such a state, if you did set it up, is at a negative temperature, believe it or not. Basically meaning there is a population inverions, with more excited states populated than ground states, and is a process fundamental to laser operation.
Re:Mildly disappointing (Score:2, Insightful)
Scientific American [sciam.com] (warning: loaded with ads etc)
Not for the light-hearted, a thorough review in Reviews of Modern Physics [aip.org] (subscription required, if you cannot access the article, drop me an email at karvind@NOSPAM.gmail.com)
On Ferroelectric spintronics [colossalstorage.net] from Colossal Storage.
Spintronics and Quantum Dots [unibas.ch]. Discussion about one possible implementation.
Another good introduction [aist.go.jp].
Hope it helps.