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IBM, Stanford team up on spintronics

Posted: 30 Apr 2004 ?? ?Print Version ?Bookmark and Share

Keywords:ibm? semiconductor? stanford university? spintronics?

Can chipmakers somehow find a way to defy Ohm's Law by working with an electron's spin instead of its charge? Scientists at IBM Corp.'s Almaden Research Center and Stanford University say they want to find out.

The two technology research powerhouses announced an agreement Monday (April 26, 2004) to work together on spintronics, a nascent discipline that blends the physics of magnetism, materials science and semiconductor fabrication.

Known as SpinAps, the new research organization is the first of its kind, say its founders. Under the agreement, Stanford students can work directly with researchers at the IBM labs here and share the resulting intellectual property.

IBM provided the seed money to fund the long-term research project, the amount for which was not disclosed.

SpinAps' goal is ambitious: To usher in a second era of electronics based on manipulating an electron's spin rather than transfer of charge.

Spin is one of the basic properties of an electron; it can rotate on its own axis in one of two opposing directions. The phenomenon was discovered in the 1920s, and has been exploited for the past 15 years by the disk drive industry in the making giant magneto-resistive heads.

Electron spin is also the working principle behind magnetic RAM devices, a type of nonvolatile memory in the prototyping stage at companies such as IBM, Motorola Inc. and Infineon Technologie AG. Later this year, IBM and Infineon plan to present a research paper describing their development of a 16Mb MRAM, said William Gallagher, senior manager of magnetoelectronics at IBM Research.

Less work has been done on using spin for logic devices, though researchers here said that's part of the plan. Using a technique known as magnetic tunneling, for example, IBM has found ways to create currents that are highly spin polarized.

"It's almost a perfect spin switch," said IBM fellow Stuart Parkin, who has done much of the basic research at IBM on spin-valve read heads and MRAMs.

The three co-directors of the SpinAps agreed there is no guarantee that their work will bear fruit any time soon, but they added it's vital to get spintronics on the fast track now. One reason is that it is proving difficult to achieve ever-higher levels of integration using traditional semiconductor scaling techniques, largely because of higher power consumption.

James Harris, professor of electrical engineering at Stanford, said he's worked with Japanese researchers on transistors that can transfer a single electron, but has come away skeptical that it can be used for commercial devices.

"When you get down to a single electron, things get really tough. There are too many variations in the properties of the device," he said.

The physics of spintronics, on the other hand, could prove to be more favorable, according Shoucheng Zhang, professor of physics at Stanford and a SpinAps co-director. He and two other researchers authored a paper last year, published in journal Science, which theorized that "spin current," which comes from angular momentum of rotating electrons, does not dissipate into heat. What's more, achieving spin current can be achieved at room temperature, he said.

One early goal for SpinAps is to develop new materials. At the Almaden lab, IBM has built a multichamber deposition system for this purpose.

The grand challenge, according to Harris, will be to find the materials that will allow engineers to inject, isolate and read electron spins. "It can only be done with artificially-created materials, or nanomaterials," he said.

Moreover, those materials should be compatible with silicon, which the electronics industry has grown dependent upon. "You can't ignore a tera-dollar investment. You have to grab a hold of that," he said.

- Anthony Cataldo

EE Times

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