Slashdot Mirror
Spintronics in your Future?
slugfro writes: "Do faster boot times and RAM that maintains memory after shutdown sound interesting? This article by a Science Magazine author details the study of utilizing the spin of electrons rather than just the charge in electronic devices (hence the name 'Spintronics'). Anyone out there researching this or have more info?" We do a story about MRAM every four months or so, and each time commercial development is a few years in the future. :)
The cheap solution for persistant RAM is to provide a constant power source for your RAM from either some form of battery or just a power source that is always on.
Where this stuff is actually useful is for better Hard Drives. In fact it's already being used for that, and has been for a while.
Not really. It's basically as binary as traditional computing, just using a different measure for "on" and "off": "up" and "down". Look:
Just like the positive/negative duo of charge, the 0s and 1s of current information technology, this up/down pairing makes spin an attractive possibility for encoding and carrying information electronically.
The "quantum-readyness" of this technology is the same as charge. The cat is spinning both upand down at the same time, until you open the box.
If you fall off a building, go real limp, because maybe you'll look like a dummy and people will be like hey, free dummy
An Intro to Spintronics - Univ. of Maryland
Article on Unisci about research into electronic spin in electronic devices
This would be so great for portable computers.
Imagine keeping a laptop/handheld with you wherever you go, but only having it on when you need it. You can instantly close the lid on it, shutting off it's power. This would preserve battery life to possibly many days at a time for a traveler. Then when you need to use the computer, just open the lid, and it's exactly where it was when you closed it.
Desktop computers would also be nice to instantly shut off and turn on at the same state, but the portable computer market seems much more useful, especially for conserving battery life.
www.Beyond7.com Insane modern art water sculpture.
So .. when your disk drive needs repair .. take it to a quantum mechanic...
A feeling of having made the same mistake before: Deja Foobar
You would go and bring the cat into this, wouldn't you. Can't you just leave him out of it. As if that poor thing hasn't been through enough with the radiation... now you want to find out what happens when you spin it too? Leave the poor thing alone, already.
Yeesh... I'm calling the humane society you sick puppy! heh.
-Alex
More of this here: http://www.physics.umd.edu/rgroups/spin/intro.html
Yes. Lets all pray that someday the scientific community will develop some sort of hardware based solution that will allow us to freeze or "pause" a computer game.
As to the spin and orbital properties of an individual atom, particularly the risk which comes with such a density of memory, what could easily and commonly affect these properties? Strong RF? Magnetic fields? Xrays? (note: laptops currently survive airport Xrays, but I'm clueless as to how this happens and whether it's something that eventually will catch up with data stored on hard drives.)
A feeling of having made the same mistake before: Deja Foobar
Tom.
Oh arse
What the hell is photocanonics? There is no such thing!
Under capitalism man exploits man. Under communism it's the other way around.
The technology works real nice. I did technology development project management for the Air Force in the late 80s on this and other wild-ass NVM technologies. MRM is very sound, just too pricey for commercial use yet. The problem is that the manufacturing economics combined with market perceived risk keeps it from prime time. Flash (the next nearest alternative) is more mature, more familiar and comfortable (derived from EPROM and E^2PROM technologies which are 25-plus years old) dispite its speed and endurance shortcomings.
Is the basic phenomenon analogous in these cases? It seems like this was also reported here on /., but I can't find it right now.
A lot of people are complaining that they only reboot their machines to "clear" the RAM. And they seem to think that if Windows crashed, this new MRAM stuff will cause their computer to be in a permanent crashed state.
Well, obviously, computers making use of MRAM will have some way to purge the memory. And maybe the OS would set a flag on a normal shutdown that would tell the BIOS (or whatever it would be when this stuff comes out) that it can go ahead and just jump right to the OS (and the OS would clear that flag as it's first order of business). If the flag didn't exist, it would go through a boot sequence which involved loading the OS off a hard drive or whatever.
But let's look at the advantages of having persistent RAM. If you have a journaling file system, the journal could be kept in memory without fear that it would be lost on a crash. When the system comes back up that data would be in memory and could then be used to repair the file system. Also, disk writes would be extremely fast because they could be cached and when the system is idle or when the disk is not busy, they could be written at that time instead of having to be written to a log that is physically on disk.
Maybe, programs that are running could survive an OS crash because their state would be perfectly perserved in persistent memory.
And if CPUs had persistent registers... recovering from a power failure would be seamless.
Just some thoughts.
--
"What do you want me to do? Whack a guy? Off a guy? Whack off a guy? Cause I'm married."
WARNING: Anti-Microsoft comment below. If you hate such commentary, stop reading now. I don't want to hear the needless whinning about all the Anti-Microsoft commentary. Guess what? This is Slashdot! It's part of the culture here. Do go preaching Atheism in church! Don't go accusing Slashdot of being unbiased! Simple right?
---Commentary begins---
My knee-jerk reaction to this is that this type of RAM will not compatible with any version of Windows. Microsoft Windows, by Microsoft's explicit advice, often requires a reboot (memory clearing) of the machine upon which the operating system is loaded. Very often, powering off is used as opposed to a simply "reboot" or "reset" since memory is sometimes retained after an instantaneous restart. Cold booting is often preferred and recommended. (Interestingly, Microsoft also recommends periodic re-installation of the operating system after formatting the drive... apparently, it's not only system RAM that is prone to corruption.)
While it can be said that this is true of all PC operating systems, it can more accurately be said
that it's "less true" of other PC operating systems.
Essentially, since Windows relies on the "clean machine" approach to efficient running, this memory technology is unsuitable for use with Windows without a "clear memory" switch.
Pushing forward with the notion of "clean hard drives" wouldn't it be great if Windows Hard Drives came with an instant re-format feature?
A teaching assistant (grad student) at my University was hired by the National Institute of Standards after graduation to work on quantum computing methods. According to him, they have a pretty complete theory, and have obtained some fairly large grants to actually put that theory to work. Some of the things he talked about sounded really incredible.
t io ns.html
I found a Scientific American article from 1996 which details some of the their work, as well as the work of others, plus a lot of useful links.
http://www.sciam.com/explorations/091696explora
I remember first reading about using electron spin in quantum computing way back in 1994, in a NY times science edition.
Not really. It's basically as binary as traditional computing
Yes, but this could open the door to the possibility of trinary computing. If circuit technology becomes "spintronically" advanced, then instead of the normal two state system (on and off) there would be three states: off, on(up), and on(down). Of course, off would still be a single state, because there is no spoon... I mean, spin... without the electron. :)
How about using an etch-a-sketch for storage? Black dots mean 0, clear spaces mean 1. If you get nailed with a virus, you can erase the storage by picking up your computer and giving it a good shake. Oh, I guess that means simply moving your computer could create some hassles. Nuts... have to works the bugs out of the idea.
File under 'M' for 'Manic ranting'
I already have one of those... It's called a PowerBook. Close the lid, and it goes to sleep in a fraction of a second and can remain that way for at least 2 weeks. Open it up and push any button, and 1 second later you're precisely where you left off...
"by a Science Magazine author"
You read it closely enough to see "a", but not see "author"?
Get some glasses!
There are several groups working on spintronics-related research around the globe. You can check some of the research the spin-doctors are working on by looking at the Spintronics 2001 Conference webpage. Some incredible results involved researchers injecting spin-polarized current into an LED and producing Circularly Polarized Light!!! Other researchers are trying to produced spin-transistors, to switch/amplify spin-polarized currents. Many of the recent challenges involve producing spin-polarized currents, finding materials that can transport electron-spin, and injecting spin-polarized electrons into semiconductors.
The Chien group here at JHU has been the first to demonstrate experimentally the existence of a half-metal. Crystals of CrO2 have been shown to have spin-polarization of 96%. This was measured at the superconductor/ferromagnetic interface through Point-Contact Andreev Reflection (PCAR) techniques.
I'll explain some of the current concepts of spintronics, but pardon any errors as I haven't really begun my research yet. The manipulation of electron spin is an extra degree of freedom that novel electronic devices can exploit. Spintronics has already, since 13 years after the discovery of GMR (Giant Magnetoresistance) in 1988, penetrated the technology industries (magnetic storage). It's rare for such new technology like this to be commercially available so soon after its discovery. Transistors were one such monumental achievement, the first Ge transistors were available within years of the transistor's invention.
GMR is an effect that occurs with a normal metal film that is sandwiched between two ferromagnetic layers. Depending on whether the spins of the ferromagnetic layer are parallel or anti-parallel, a significant change of resistance is measured across the structure. A more useful device which extrapolates off this concept is a spin-valve This is the standard GMR trilayer, with an anti-ferromagnetic layer on the bottom. This layer pins the spin of the bottom Ferromagnetic layer. The top ferromagnetic layer can then float, and have it's spin affected by the external magnetic field. This in turn creates a magnetic-field-dependent resistance across the device. Sensitive measurements of the magnetic field, obtained by measuring resistance, can be obtained in this manner .This magnetic-field-dependent resistance is known as Magnetoresistance. This concept, in a fundamental sense, is how the newer GMR-based read-heads on high-density hard drives operate.
Another similar device is the Magnetic Tunnel Junction . This is similar to the GMR trilayer, but an insulator film is sandwiched between the ferromagnetic layers, instead of a normal metal. Current can then tunnel through the device, again dependent on whether the spins are parallel or anti-parallel in the ferromagnetic layers. The tunnel junction is the fundamental concept at the core of the MRAM's.
Another exciting area of research with spintronics that I haven't heard anybody on slashdot mention yet is quantum computing. Electrons are spin-1/2 fermions, and hence have two distinct eigenstates of the Spin operator (the eigenstates are usually called "spin-up" and "spin-down"). This makes them perfect candidates for representation of quantum bits (qubits) for potential quantum computation. Some groups are working on this idea, by studying interactions of quantum dots for instance.
Overall, this is a budding field that has already impacted the technology industry in it's scant 13 years of existence. Expect many more interesting and potentially groundbreaking discoveries to occur. But then again, I'm spin-biased. :-)
make world, not war
Sounds a lot like the write-only drive I developed in the 80's while a physics student in college. It used the Pauli Exclusion and Heisenberg Uncertainty principles to store tremendous amount of information. Problem was, I couldn't get the informaton back out.
A guy called after reading our April edition of our user's group newsletter and asked if I had patented the idea and wondered if we could send him a prototype. Shortly thereafter, he received a bakelite case with a SCSI cable coming from it. He hooked it to his Mac. Took the guy three phone calls before he understood it was all a joke.
Can I claim prior art here?
Measurement of the spin-polarization was done through Point-Contact Andreev Reflection (PCAR) measurements at the interface of a superconductor/ferromagnetic. Ie, at the interface between the CrO2 crystal and a sharp-tipped lead superconductor in the vicinity of 4K (maybe colder).
For more info, see my other post further down on this slashdot article.
make world, not war
Uptime in weeks?
[tim@cr660477-a tim]$ uptime
5:15pm up 118 days, 19:01, 6 users, load average: 0.00, 0.02, 0.00
[tim@cr660477-a tim]$ cat
Red Hat Linux release 7.1 (Seawolf)
Kernel 2.4.2-2 on an i586
</brag>