Missing Link of Electronics Discovered: "Memristor"

sciam.com ^ | May 1, 2008 | JR Minkel

[neverdem]

Memory plus resistor may add up to longer-lasting batteries and faster-booting computers

After nearly 40 years, researchers have discovered a new type of building block for electronic circuits. And there's at least a chance it will spare you from recharging your phone every other day. Scientists at Hewlett-Packard Laboratories in Palo Alto, Calif., report in Nature that a new nanometer-scale electric switch "remembers" whether it is on or off after its power is turned off. (A nanometer is one billionth of a meter.)

Researchers believe that the memristor, or memory resistor, might become a useful tool for constructing nonvolatile computer memory, which is not lost when the power goes off, or for keeping the computer industry on pace to satisfy Moore's law, the exponential growth in processing power every 18 months.

You may dimly recall circuit diagrams from your middle school science class; those little boxes with a battery on one end and a lightbulb on the other. Ring any bells? To an electrical engineer, the battery is a capacitor—a device for storing electric charge—and the lightbulb is a resistor—an obstacle to electric current. Until now, engineers have had only one other basic element to work with—the inductor, which turns current into a magnetic field.

In 1971 researcher Leon Chua of the University of California, Berkeley, noticed a gap in that list. Circuit elements express relationships between pairs of the four electromagnetic quantities of charge, current, voltage and magnetic flux. Missing was a link between charge and flux. Chua dubbed this missing link the memristor and created a crude example to demonstrate its key property: it becomes more or less resistive (less or more conductive) depending on the amount of charge that had flowed through it.

Physicist Stanley Williams of HP Labs says that after a colleague brought Chua's work to his attention, he saw that it would explain a variety of odd behaviors in electronic devices that his group and other nanotech researchers had built over the years. His "brain jolt" came, he says, when he realized that "to make a pure memristor you have to build it so as to isolate this memory function."

So he and his colleagues inserted a layer of titanium dioxide (TiO2) as thin as three nanometers between a pair of platinum layers [see image above]. Part of the TiO2 layer contained a sprinkling of positively charged divots (vacancies) where oxygen atoms would have normally been. They applied an alternating current to the electrode closer to these divots, causing it to swing between a positive and negative charge.

When positively charged, the electrode pushed the charged vacancies and spread them throughout the TiO₂, boosting the current flowing to the second electrode. When the voltage reversed, it slashed the current a million-fold, the group reports. When the researchers turned the current off, the vacancies stopped moving, which left the memristor in either its high- or low-resistant state. "Our physics model tells us that the memristive state should last for years," Williams says.

Chua says he didn't expect anyone to make a memristor in his lifetime. "It's amazing," he says. "I had just completely forgotten it." He says the HP memristor has an advantage over other potential nonvolatile memory technologies because the basic manufacturing tools are already in place.

Williams adds that memristors could be used to speed up microprocessors by synchronizing circuits that tend to drift in frequency relative to one another or by doing the work of many transistors at once.

Whether industry will adopt it remains to be seen. In an editorial accompanying the paper, nanotech researchers James Tour and Tao He of Rice University in Houston note that "even to consider an alternative to the transistor is anathema to many device engineers, and the memristor concept will have a steep slope to climb towards acceptance."

But the memristor concept is a promising one, they wrote, adding: "It is often the simple ideas that stand the test of time."

[neverdem]

SET IT AND FORGET IT: A new device called a memristor "remembers" whether it's on or offwhether or not it has power. Shown here 17 memristors in a row, formed by crossing 17 platinum nanowires with another wire, with a thin dab of titanium dioxide sandwiched between each junction. Each wire is 50 nanometers wide, equivalent to about 150 atoms.
Image courtesy of J. J. Yang, HP Labs.
Missing link' memristor created: Rewrite the textbooks?

H.P. Reports Big Advance in Memory Chip Design

The missing memristor found Link to Nature abstract

[neverdem]

Thanks for your thread!

[4buttons]

“(A nanometer is one billionth of a meter.)”

or, .00000000001 of a football field. (they always use this conversion)

[neverdem]

You Name It, and Exercise Helps It

China puts nation on alert to try to stop deadly virus

New immune treatment may control AIDS virus

FReepmail me if you want on or off my health and science ping list.

[the invisib1e hand]

"remembers" whether it is on or off after its power is turned off.

I'm sure that's a handy feature.

[Sawdring]

If this doesn’t work for Chua, he will have to punt.

[dljordan]

Thanks, I love this stuff.

[Squantos]

Wow.......

[CarrotAndStick]

I'm sure that's a handy feature.

 

 

HP's Memristor Could Eliminate Boot Times

Thursday, May 1st 2008 @ 6:00 AM

By Nick Mokey
Staff Writer, Digital Trends News

http://news.digitaltrends.com/news/story/16558/hps_memristor_could_eliminate_boot_times

 

The discovery of a fourth circuit element at HP's labs, a so-called "memristor," could drastically change the way personal computers operate in the future.

If you ever took a basic electronics course in high school and managed not to spend the entire time burning your name into a workbench with a soldering iron, chances are you remember resistors, capacitors and inductors as the three fundamental passive circuit elements. However, engineers at HP believe they may have discovered a fourth fundamental circuit element: a memory resistor, or “memristor.” The new component retains history of the information it has acquired, and has the potential to significantly change the landscape for personal computing.

The team of four researchers, led by R. Stanley Williams, published their paper in Thursday’s edition of Nature. The memristor they developed actually changes resistance depending on what voltage has been applied to it in the past, creating the potential for systems that can be powered off and powered on again without the usual boot-up required of ordinary systems. Although the existence of such an element has been speculated about since 1971, Williams and his team were the first to cook up a working example and publish their findings.

“To find something new and yet so fundamental in the mature field of electrical engineering is a big surprise, and one that has significant implications for the future of computer science,” said Williams, in a statement.

Since the non-volatile memory currently used to “remember” system states when they are turned is fairly power  hungry, HP envisions systems with memristors being used to save energy on a large scale, such as with data centers. On a more personal level, it could also be used to refine existing computer processes that mimic the human brain, such as facial recognition.

[mjp]

Electronic theorists have been using the wrong pair of variables all these years—voltage and charge. The missing part of electronic theory was that the fundamental pair of variables is flux and charge,” said Chua. “The situation is analogous to what is called “Aristotle’s Law of Motion, which was wrong, because he said that force must be proportional to velocity. That misled people for 2000 years until Newton came along and pointed out that Aristotle was using the wrong variables. Newton said that force is proportional to acceleration—the change in velocity. This is exactly the situation with electronic circuit theory today. All electronic textbooks have been teaching using the wrong variables—voltage and charge—explaining away inaccuracies as anomalies. What they should have been teaching is the relationship between changes in voltage, or flux, and charge.”

[raygun]

ping

[RightWhale]

Sceptical that this would be a missing component of an AC circuit. Got math?

[RightWhale]

using the wrong pair of variables all these years

Not possible to use the wrong ones if they all appear in the equation.

[JRandomFreeper]

R, L, and C work just fine for most of what I want to do.

Is it just me, or does this sound like a PIN diode?

/johnny

[RightWhale]

Yes, it does sound that way.

[ThePythonicCow]

When positively charged, the electrode pushed the charged vacancies and spread them throughout the TiO2, boosting the current flowing to the second electrode. When the voltage reversed, it slashed the current a million-fold

Aha - that explains this better than I had seen before.

The difference is not (as I had thought earlier) between having the holes near the top or near the bottom of the titanium dioxide.

Instead, the difference is between having the holes (missing oxygen atoms) compacted near the top of the titanium dioxide or dispersed throughout it.

When the holes are near the top, then the lower portion of the titanium dioxide, lacking the holes, presents great resistance. When the holes are dispersed, then the entire layer of titanium dioxide conducts easily, and one can see much lower resistance between the two overlapping wires.

Thanks for posting this.

[Jonx6]

ping

[ThePythonicCow]

Two big differences between this and the typical diode.

This device is very rapidly (faster than HP Labs has been able to measure, as I recall) reversible in state. Diodes have their directionality baked in at the factory.

And the other difference is that it is not a diode. That is, current does not flow one way more easily than the other.

Rather, this device is either a plain old resistor, or a plain old conductor ... which state, as noted, can be switched very quickly.

[21stCenturion]

...

[sionnsar]

After 40 years? Qualifies it for a Geezer Geek ping!

Geezer Geek ping.

This is a very low-volume ping list (typically days to weeks between pings).
FReepmail sionnsar if you want on or off this list.