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New Memristor Makes Low-Cost, High-Density Memory
KentuckyFC writes "A group of electronics engineers have discovered that a thin layer of vanadium oxide acts as a memristor, the fourth basic component of circuits after resistors, capacitors, and inductors that was discovered last year. At a critical temperature, a current passing through the layer causes it to change from an insulating state to a metal-like state, thereby changing its resistance (abstract). The effect lasts many hours — which is what makes the layer a memristor (a resistor with memory). The team says this could be scaled up to make resistive random access memory, or RRAM, at very low cost, from little more than layers of vanadium oxide."
"The effect lasts many hours â" which is what makes the layer a memristor (a resistor with memory). The team says this could be scaled up to make resistive random access memory, or RRAM, at very low cost, from little more than layers of vanadium oxide.""
If this was going into a SSD then it would have to last longer than that.
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I thought the more exciting announcement was that memristors could be tripled up to create transistors that were (despite being tripled up) still much smaller than a standard transistor.
Then, there were bits about them supporting more than just binary states, which would increase complexity and density yet again.
Denser memory may be the first pratical consumer product, but if the other possiblities work out, I'm pretty sure that memory will also be the least significant.
" At a critical temperature,"
"Gee, I had it stored on this memsistor chip - but I left it in my shirt pocket, and my data melted."
The article doesn't say what temperature, so there's probably an issue there. Until that issue is solved, it's about as useful as write-only memory.
Also, looking at the required voltage (50 volts @ 0.6 amp), this is NOT going to be either high-density, or portable,or particularly energy-efficient.
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resistance changing based on past... fuses do that too!
calling it passive doesn't seem right.
Also, this doesn't seem that novel. That's why it may be great!
I've seen this statement repeated about memristors. Many devices cannot be duplicated with L's, C's and R's (diodes, fuses, etc.). Those parts all have one thing in common, they are nonlinear and/or time varying. Memristors are not LTI and therefore not a "fourth type" of circuit element.
But how does memristor differ from NTC or PTC resistors that change resistance on temperature (i.e. caused by current flow) and the effect lasts for a while (ultil the resistor cools down)?
No more need to supercool RAM on seized computers in order to extract passwords - the RAM will just naturally hold state for hours.
If they're going to use this, (some) people are going to want to have more secure operating systems that don't leak security data all over the place.
http://en.wikipedia.org/wiki/Memristor#Potential_applications
[27] http://www.nytimes.com/2008/05/01/technology/01chip.html
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I didn't know that resistors, capacitors, and inductors were only discovered last year. Wow, that's really cool! Now we can start making really cool electrical gizmos as opposed to what we've been using these last hundred years or so.
Sorry to be so harsh, but the specific experiment reported here is of little to none value outside of science. Why?
Hysteretic resistive switching in metal oxide systems is a well known phenomenon (RRAM) and occurs in all transition metal oxides with noble eletrodes. This is what has been recristened as "Memrestor" by HP. It is widely agreed upon that this switching mechanism is due to a redox reaction where oxygen is added or removed from the insulator. The specifics (filament, interfacial barrier lowering etc.) are still subject of current research though.
The experiment in the paper takes a slightly different approach: vanadium oxide has a very interesting property where its resistance switches apruptly by orders of magnitude at a certain temperature due to a reorganisation of its electronic structure. This phenomenon is known as metal to insulator (MTI) transition and has been research for at least 50 years.
The MTI has a hysteretic behavior which means that it retains its state if you vary the temperature only a little above or below the critical MTI temperature Tc. The researchers have now shown that if you keep the temperature of the system close to Tc, you can use an additional electric current to switch the resistivity of the system. A possible explanation could be self heating.
Why is it useless for practical application?
1) The phenomenon instrinsically only works at a certain temperature. Deviations by fractions of degrees K will destroy all information.
2) As far as I can see they only demonstrated electrical switching into one direction. To erase the memory both would be required.
All in all a nice experiment, but again with typical university style hype, piggybacking on the Memristor craze.
I am also relatively certain that current driven MTI switching has been reported before. I am aware of a couple of experiments where a field switched MTI transition was proposed for transistors. Those devices should exhibit exactly the same hysteresis and "memory" properties.
These things are not invariants. They are in the same class as magnetic core memories/hard drives or DRAM, i.e. they retain for a time a change in their electrical state. They may be a better future short term memory technology than either, though this is yet to be shown. But there is nothing fundamentally theretically new about them.
From scarped cliff or quarried stone she cries "A thousand types are gone, I care for nothing, no not one."
Think of the short-term memory in your brain. Not everything needs to be stored for a long time. Many things only need to be stored transiently, and this could be fine for that purpose.
> resistors, capacitors and inductors that were discovered last year
Wow, I don't know how we made ANYTHING until last year !
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. . . just posting this in the very unlikely chance that a competent USPTO employee (I know you're out there) is not only reading this thread but also is assigned related patents.
IMHO this kind of development is worthy of a patent; it includes a brand-new type of component, with no prior art in a single component appearing to exist, and a method by which it is manufactured.
Now, I expect patent trolls will start the patenting insanity with "it's a PDA, but with memristors" and "it's a phone, but with memristors" and "it's an instant-on PC, but with memristors" and in all of those cases I would say that the patent should not be allowed, because those are "innovations" which are obvious to those skilled in the art.
Also, the software to store to memristors should not be patentable. "method by which data is semi-permanently stored in a memristor-based storage device" should not be patentable, because that skill (putting data in memory or storage) is obvious to every literate computer user, let alone software engineers.
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if you're that paranoid, it's fairly easy to have the OS wipe all user & program data from the memory at shutdown.
IMO that is no solution. A system can be easily reset/halted before an OS has a chance to neatly shut down.
Creating "Security RAM" modules would be more effective: Equipped with a capacitor for power, they could self-wipe at the hardware level when they detect a reset signal or power interruption. Given the precarious nature of info esp. on laptops, one would think this category of RAM would have already been developed.
The memristor is is just a way to model nonlinear circuit elements and is one of many components in a nonlinear expansion for circuit modeling. See this paper by Leon Chua, the memristor's inventor. Note that in this paper the fourth element of the four element torus is negative resistance and not the memristor. All of the publicity over the memristor has been (sucessfull) marketing by some researchers at HP. .
From the talk page for the memristor on wikipedia
"Resistance, Capacitance and Inductance are regarded as fundamental because to each there corresponds a different picture of what is going on with the energy. Resistance refers to the loss of energy to Joule heating. Capacitance refers to storage of energy in the electric field. Inductance refers to storage of energy in the magnetic field.
If memristance is the "fourth fundamental" circuit element then memristors must do something with the energy they are imparted other than turn it into heat, or store it in electric or magnetic fields. So what do memristor supporters have to say about this? nothing. This is not surprising, since the concept of memristance stems from a purely mathematical argument bent on taming the current/voltage relationships of nonlinear circuit elements. The concept of memristance was invented out of convenience to avoid dealing with frequency-dependent (time-dependent) resistance, inductance, and capacitance. Thus the memeristor is not "fundamental", unless in your book fundamental is synonymous with convenient."
at the cost of dropped vowels?
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How does this relate to a resistor which undergoes a discontinuous resistance change under critical conditions? Can you explain how it relates to the advertised device? Where is the charge being stored? Please continue to assume that I'm stupid, and explain the reasoning. My electromagnetic theory is thirty five years in the past now.
From scarped cliff or quarried stone she cries "A thousand types are gone, I care for nothing, no not one."
The real news here is that we have a totally new circuit element and heaven only knows where that can take us.
Exactly how is this a fundamentally new circuit element? Most ohmic resistors change their resistance when a current is passed through them because the current causes heating and the heating changes their resistance. Since they take time to cool down they will have a (rather limited) memory too.
Yes this is a very interesting device and vastly more practical in terms of applications for memory but, unless it does something the articles do not mention, calling it a new fundamental circuit component seems wrong because it appears that you can mimic its behaviour using a well insulated piece of wire. Of course the wire is not very useful in terms of applications (outside electric heaters and light bulbs) but nevertheless it is a resistance whose value depends on previous current history.
It looks to me as though there is a confusion. The original vanadium oxide film when nonconducting can store supplied charge in a magnetic field. But the switching behaviour doesn't seem to be anything to do with this, unless there is some explanation not given in the article.
I guess someone from man.ac.uk ought to be interested in electronic storage, seeing as how you started off using cathode ray tubes:-)
From scarped cliff or quarried stone she cries "A thousand types are gone, I care for nothing, no not one."
I don't think this 'memristor' is suitable, at least in its current incarnation, to create Solid-State hard drives. Why not? It only retains your info for several hours. So, that essentially limits it to use as RAM. But RAM shouldn't store data for several hours.
The distinction here is that, on the hard drive, the data is always encrypted, but in RAM, it must be decrypted. I don't mind the hard drive storing the *encrypted* data for years, but I don't want my memory storing decrypted data for hours after I shut off my computer.
Now, that said, I could see, possibly, one application for this technology - used as a very large, very high-speed 'cache' in an otherwise conventional hard drive. That is, instead of the computer transferring data directly to/from the HD platters, it would read the data and write changes to the cache, then the hard drive would synchronize any changes in the cache back to the platters. Would, no doubt, speed up games and databases tremendously having a 100 GB high-speed cache. The key here is, if you have encrypted data, it is always encrypted in this cache (since the cache is just part of the hard drive), while your RAM is of a more 'conventional' nature that loses its state a few seconds or minutes after shutdown. Heck, with this tech, if your computer loses power, if the power comes back on within an hour or two, the hard drive could finish writing changes from the semi-persistent cache to the disk before bootup, so you minimize data loss.
Thanks for citing the ieee paper http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=1083337. Unfortunately I am not a current member. Can the entire paper be found anywhere else online? Thanks this is a very interesting discussion.