Researchers develop first high-temperature spin-field-effect transistor

Dec 23, 2010

An international team of researchers featuring Texas A&M University physicist Jairo Sinova has announced a breakthrough that gives a new spin to semiconductor nanoelectronics and the world of information technology.

The team has developed an electrically controllable device whose functionality is based on an electron's . Their results, the culmination of a 20-year scientific quest involving many international researchers and groups, are published in the current issue of Science.

The team, which also includes researchers from the Hitachi Cambridge Laboratory and the Universities of Cambridge and Nottingham in the United Kingdom as well as the Academy of Sciences and Charles University in the Czech Republic, is the first to combine the spin-helix state and anomalous Hall effect to create a realistic spin-field-effect transistor (FET) operable at high temperatures, complete with an AND-gate logic device — the first such realization in the type of transistors originally proposed by Purdue University's Supriyo Datta and Biswajit Das in 1989.

"One of the major stumbling blocks was that to manipulate spin, one may also destroy it," Sinova explains. "It has only recently been realized that one could manipulate it without destroying it by choosing a particular set-up for the device and manipulating the material. One also has to detect it without destroying it, which we were able to do by exploiting our findings from our study of the spin Hall effect six years ago. It is the combination of these basic physics research projects that has given rise to the first spin-FET."

Sixty years after the transistor's discovery, its operation is still based on the same physical principles of electrical manipulation and detection of electronic charges in a semiconductor, says Hitachi's Dr. Jorg Wunderlich, senior researcher in the team. He says subsequent technology has focused on down-scaling the device size, succeeding to the point where we are approaching the ultimate limit, shifting the focus to establishing new physical principles of operation to overcome these limits — specifically, using its elementary magnetic movement, or so-called "spin," as the logic variable instead of the charge.

This new approach constitutes the field of "spintronics," which promises potential advances in low-power electronics, hybrid electronic-magnetic systems and completely new functionalities.

Wunderlich says the 20-year-old theory of electrical manipulation and detection of electron's spin in semiconductors — the cornerstone of which is the "holy grail" known as the spin transistor — has proven to be unexpectedly difficult to experimentally realize.

"We used recently discovered quantum-relativistic phenomena for both spin manipulation and detection to realize and confirm all the principal phenomena of the spin transistor concept," Wunderlich explains.

To observe the electrical manipulation and detection of spins, the team made a specially designed planar photo-diode (as opposed to the typically used circularly polarized light source) placed next to the transistor channel. By shining light on the diode, they injected photo-excited electrons, rather than the customary spin-polarized electrons, into the transistor channel. Voltages were applied to input-gate electrodes to control the procession of spins via quantum-relativistic effects. These effects — attributable to quantum relativity — are also responsible for the onset of transverse electrical voltages in the device, which represent the output signal, dependent on the local orientation of processing electron spins in the transistor channel.

The new device can have a broad range of applications in spintronics research as an efficient tool for manipulating and detecting spins in semiconductors without disturbing the spin-polarized current or using magnetic elements.

Wunderlich notes the observed output electrical signals remain large at high temperatures and are linearly dependent on the degree of circular polarization of the incident light. The device therefore represents a realization of an electrically controllable solid-state polarimeter which directly converts polarization of light into electric voltage signals. He says future applications may exploit the device to detect the content of chiral molecules in solutions, for example, to measure the blood-sugar levels of patients or the sugar content of wine.

This work forms part of wider spintronics activity within Hitachi worldwide, which expects to develop new functionalities for use in fields as diverse as energy transfer, high-speed secure communications and various forms of sensor.

While Wunderlich acknowledges it is yet to be determined whether or not spin-based devices will become a viable alternative to or complement of their standard electron-charge-based counterparts in current information-processing devices, he says his team's discovery has shifted the focus from the theoretical academic speculation to prototype microelectronic device development.

"For spintronics to revolutionize information technology, one needs a further step of creating a spin amplifier," Sinova says. "For now, the device aspect — the ability to inject, manipulate and create a logic step with spin alone — has been achieved, and I am happy that Texas A&M University is a part of that accomplishment."

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User comments : 18

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Quantum_Conundrum
3 / 5 (2) Dec 23, 2010
Yeah, I agree, we are approaching the limits of 2-dimensional, caveman, flatland technology.

Other than expansion slots like PCI/Express, we haven't even done anything in 3-d yet...
Quantum_Conundrum
2 / 5 (4) Dec 23, 2010
Think about this. Our existing electronic computers do not even use 3d. They are like an electrician who is wiring your house, and he hasn't figured out yet that he can run wires through the attic and spaces between joists as well as the back wall, but instead only runs wires through the front wall and two or three internal walls. Moreover, we've ignored the second and third floors, having left them unused, and not even considered the modern skyscraper.

In terms of spatial composition, our existing computer technology is one of the most primitive and under-developed technologies in the history of humanity.

Travel to a warehouse or a port, and look how things are stacked. Then look at our sad and pathetic computer architecture. It's shameful.
thales
5 / 5 (1) Dec 23, 2010
"We used recently discovered quantum-relativistic phenomena for both spin manipulation and detection to realize and confirm all the principal phenomena of the spin transistor concept," Wunderlich explains.


That's pretty kick-ass.

Quantum_Conundrum
2 / 5 (4) Dec 23, 2010
Yeah, but this gives rise to some interesting and fundamentally world changing questions for the world of high level computer programming.

For example, seeing as how a spin-tronic bit can be both on and off at the same time, how does this effect logic operations based on the comparison of variables and constants?
Example 1:
If (A = 1)
Do Something;
Else
Do Something else;

If A is "Both 1 and 0" the "Else" will get skipped, moreover you cannot force the "else" to execute even by nesting it inside another "If". How would you go about rigging "If/then/else" situations to always get the result the programmer intends to get? Perhaps add a "both" key word? "If/then/both/else"?

Example 2:

switch A
case 0:
Do something;
case 1:
Do something else;

If A is "both 1 and 0" then both of these statements will execute, unless the statement following "case 0" changes the value of A to "0, but not 1," unless both statements are executed simultaneously, er...how?
Ratfish
not rated yet Dec 23, 2010
I don't think there are too many if/then/else statements attached to binary inputs. This would require a new assembly language though.
CHollman82
not rated yet Dec 23, 2010
You're wrong QC, ever heard of multi-layer PCB's...?

Also, 3D circuit design is difficult, and 3D circuit production is almost impossible with current methods... add to that the fact that analog and digital noise would be extremely difficult to isolate on 3 dimensional circuits.
Quantum_Conundrum
2.3 / 5 (3) Dec 23, 2010
I don't think there are too many if/then/else statements attached to binary inputs. This would require a new assembly language though.


Not so fast...

Video games tend to use a LOT of binary inputs, people just don't realize it. I used to mod starcraft, and almost everything in the game that you would want to mod was controlled by individual on/off bits stored in the respective files in the mpq archives.

How do you deal with situations like converting numbers from one variable type to another.

Not only would they need to restrict arithmetic across types, but they would even need to restrict conversion of types, because converting "A" to an integer and then adding it to "int B" would be a disaster. Then "B" might end up equaling 5 and 6 at the same time...

If your computer crashes, how do you do a "clean" restart, since "spin" doesn't turn off with a power down or reset...you're corrupt 4ever?!
thales
not rated yet Dec 23, 2010
If A is "both 1 and 0" then both of these statements will execute, unless the statement following "case 0" changes the value of A to "0, but not 1," unless both statements are executed simultaneously, er...how?


I think that's the whole idea - that multiple parallel computations can be done simultaneously.
thales
4.5 / 5 (2) Dec 23, 2010
If your computer crashes, how do you do a "clean" restart, since "spin" doesn't turn off with a power down or reset...you're corrupt 4ever?!


You rig the computer to trigger a gun to kill the user if it crashes. That way the user is always in a universe where the computer works.

http://en.wikiped...periment
Ratfish
not rated yet Dec 23, 2010
Not so fast...

Video games tend to use a LOT of binary inputs, people just don't realize it. I used to mod starcraft, and almost everything in the game that you would want to mod was controlled by individual on/off bits stored in the respective files in the mpq archives.


I too have dealt with similar config files, but even though they employ 1s and 0s for their state, I don't believe that it's truly binary. That variable could be anything.

I don't really see this as being on and off at the same time, I see it as being on or off and something else so each electron has multiple dimensions and thus carries more information. No idea how this would work in the context of a computer though.
Quantum_Conundrum
2.3 / 5 (3) Dec 23, 2010
I don't really see this as being on and off at the same time, I see it as being on or off and something else so each electron has multiple dimensions and thus carries more information. No idea how this would work in the context of a computer though.


One interpretation is that you can convert numbers, letters, and other data to "base 3" using "0,1, both" as "0,1,2" to store data using fewer switches in memory.

So 255 is the highest number you can store with 8 bits.

But you could store 0 to 242 on just 5 switches in base 3.

So by this interpretation, you could obtain a much higher data density just by base 3 > base 2...
Quantum_Conundrum
3 / 5 (2) Dec 23, 2010
You're wrong QC, ever heard of multi-layer PCB's...?

Also, 3D circuit design is difficult, and 3D circuit production is almost impossible with current methods... add to that the fact that analog and digital noise would be extremely difficult to isolate on 3 dimensional circuits.


Optical Bus

Look at all the plasmonic lasers and quantum dot photodetectors, etc.

Problem solved. You can have the best of both worlds.

I'm not just talking about connecting 2 or 3 boards together. I'm talking about a radically advanced cubical architecture based on spintronics and optics, which has far less waste heat.

And yeah, we can't build this was caveman lithography. We need nano-assembly eventually.
DamienS
5 / 5 (3) Dec 23, 2010
seeing as how a spin-tronic bit can be both on and off at the same time, how does this effect logic operations based on the comparison of variables and constants?

It doesn't. The underlying physical representation doesn't affect high-level programming languages. You're simply exploiting electron spin instead of charge at the physical level.
dtxx
3.8 / 5 (4) Dec 24, 2010
Thank you so much QC. Call intel immediately. I'm sure no one there has ever even thought of expanding processors in the vertical dimension. You seem to be constantly ranting about your amazing ideas lately. You're just blowing hot air and your comments make it clear you have no knowledge of processor hardware and how it is designed. I used to just think you were a cultist, but now I'm starting to think of you in a similar light to zephyr with his inept dense aether madness. Open your computer and look at the size of the heat sink and active cooling solution required for a single layer chip. You don't need extensive starcraft modding experience to draw a conclusion from that.
Quantum_Conundrum
2 / 5 (4) Dec 24, 2010
dtxx:

I know about the cooling issues.

My goodness, you're dense.

When they have spintronic and optical computers they aren't going to need nearly as much cooling because they can operate at much lower energy levels, and even have non-volatile ram. So MOST of the cooling issues go away. That's one of the main purposes of spintronics and "MRAM".

Do you realize almost the entire chip in a modern processor is space that is wasted by issues like feature size, cross talk, and geometric limits of 2 dimensions, as well as interface issues with the board(s)? The transistor size definitely isn't even what's limiting the size of a chip.

It amazes me that you have to "translate" plain english for everyone.

YOU WILL NOT NEED 1/100TH OF COOLING WHEN YOU HAVE "MRAM" AND "MCACHE" AND SPINTRONIC OR OPTICAL TRANSISTORS AND BUSES. THAT'S THE WHOLE POINT OF THE TECHNOLOGY TO SAVE ON ENERGY COSTS AND WASTE HEAT, WHILE MAKING IT SMALLER AND FASTER.
bugmenot23
not rated yet Dec 24, 2010
Looks like this QC user just learned about the "caps lock" key. Sigh.
Quantum_Conundrum
not rated yet Dec 24, 2010
Looks like this QC user just learned about the "caps lock" key. Sigh.


Well, I'm sorry if I offend anyone, but the guy was arguing against an issue that won't even exist.

these other technologies that are being constantly proven in a lab lately are going to make all of his concerns go away.

Spintronics means MRAM only uses energy when a bit's value is actually being changed, and even then only about 1/100th as much.

Thermo-electric devices will absorb some of the waste heat and make it back into electricity.

nano and micron scale lasers plus quantum dot photo-detectors means that in many cases you won't even have physical buses any more, instead of a wire, a laser will beam data across the board, and especially between boards, which saves a huge amount of space an energy on the motherboard and add-on cards.
mjesfahani
not rated yet Dec 30, 2010
I guess it can replace the spoilt FETs like LDMOS!

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