Spintronics: computation and memory technology using electron spin

We're happy to announce a new section to Spintronics-Info: Research centers. We hope that this will be a comprehensive index for Spintonics related research centers around the world. If you know of some place we missed, please contact us.

In the meantime there are only two centers listed, but hopefully we'll start adding more soon. 

A small ribbon made of the carbon honeycomb pattern found in graphite and nanotubes could display intriguing electronic properties and serve as a material for spin-based electronics (spintronics), researchers have predicted.

Steven Louie's group at the University of California at Berkeley, US, has now used ab initio calculations to show that ceratain carbon nanoribbons will display half-metallicity. The researchers calculated the electronic properties of graphene sheets (the single layers of hexagonally arranged carbon atoms found in graphite). Specifically, they looked at ribbons between 1.5 and 6.7 nm wide,  with a zigzag border at each side (see image below).

The researchers found that such ribbons, if subjected to an electric field perpendicular to the ribbon length, should display half-metallic properties. They even predict that these properties should be robust against imperfections of the border structure. 

Zutic, a University at Buffalo theoretical physicist and the recipient of a prestigious National Science Foundation CAREER Award, is finding ways to introduce spintronic properties and a phenomenon called spin injection into silicon.

"For information processing and advanced logic operations, it would be particularly desirable to integrate seamlessly magnetic materials with silicon," said Zutic, Ph.D., assistant professor of physics in the UB College of Arts and Sciences. "Rather than displace all that we've learned about silicon through the decades, my work tries to build on it."

Zutic's proposal for spin injection and detection in silicon was published in July in Physical Review Letters with collaborators Jaroslav Fabian of the University of Regensburg and Steven Erwin at the Naval Research Laboratory.

Researchers at the National Institute of Standards and Technology have made the first confirmed “spintronic” device incorporating organic molecules, a potentially superior approach for innovative electronics that rely on the spin, and associated magnetic orientation, of electrons. The physicists created a nanoscale test structure to obtain clear evidence of the presence and action of specific molecules and magnetic switching behavior.

Spintronic devices usually are made of inorganic materials. The use of organic molecules may be preferable, because electron spins can be preserved for longer time periods and distances, and because these molecules can be easily manipulated and self-assembled. However, until now, there has been no experimental confirmation of the presence of molecules in a spintronic structure. The new NIST results are expected to assist in the development of practical molecular spintronic devices.

The experiments, described in the October 9 issue of Applied Physics Letters, used a specially designed nanoscale “pore” in a silicon wafer. A one-molecule-thick layer of self-assembled molecules containing carbon, hydrogen and sulfur was sandwiched in the pore, between nickel and cobalt electrodes. The researchers applied an electric current to the device and measured the voltage levels produced as electrons “tunneled” through the molecules from the cobalt to the nickel electrodes. (Tunneling, observed only at nanometer and atomic dimensions, occurs when electrons exhibit wave-like properties, which permit them to penetrate barriers.) 

Funded by the US National Science Foundation, researchers at Ohio University and Ohio State University have created an improved magnetic-semiconductor bilayer that they claim solves a problem spintronics scientists have been invest- igating for years ("Reconstruction Control of Magnetic Properties during Epitaxial Growth of Ferromagnetic MnGa on Wurtzite GaN(0001)", Lu et al (2006) Phys. Rev. Lett. 97, 146101).

Unlike classic or vintage electronics that operate on electronic charges, spin-based electronics focuses on the spin of electrons to carry and store information. Spintronics is predicted to revolutionize the electronics industry, say the researchers, by making devices faster, improving storage capacity and reducing the amount of power needed to run them, but the technology has not yet been widely applied, because due to difficulty controlling, manipulating and measuring the electrons.

Led by postdoctoral fellow Erdong Lu, together with Arthur Smith and David Ingram, of Ohio University of Ohio University as well as J W Knepper and F Y Yang of Ohio State University, the team has created an effective interface between a semiconductor and ferromagnetic metal. Formed from binary ferromagnetic manganese gallium (MnGa) crystalline thin films epitaxially grown on wurtzite gallium nitride (0001) surfaces using RF plasma molecular beam epitaxy, the two-layer sandwich nearly eliminates any intermixing of the two layers and allows the spin to be 'tuned'.

A gyromagnetic effect discovered by Albert Einstein and Dutch physicist Wander Johannes de Haas - the rotation of an object caused by a change in magnetization - has been measured at micrometer-scale dimensions for the first time at the National Institute of Standards and Technology (NIST). The new method may be useful in the development and optimization of thin film materials for read heads, memories and recording media for magnetic data storage and spintronics, an emerging technology that relies on the spin of electrons instead of their charge as in conventional electronics.

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In a discovery that could contribute to the emerging field of spintronics, scientists have demonstrated a way to measure the distance an electron travels in nanoscale materials before its spin is reversed due to scattering.
     
Because in spintronics, electron spin carries the information, it is important to know how far electrons can travel in a device before this spin information is lost. In a discovery that could contribute to the emerging field of spintronics, scientists at Oak Ridge National Laboratory (ORNL) and the Institute of Physics, Chinese Academy of Science, have demonstrated a way to measure the distance an electron travels in nanoscale materials before its spin is reversed due to scattering.

A UK scientist has been awarded the Degussa European Science-to-Business Award 2006 for his pioneering work on 'spintronic 'microchips. With their ability to increase the capacity of data storage by 100 times, the new microchips look set to revolutionise modern technology.

According to the Professor, his research has proven that spintronic microchips are a workable proposition which have huge implications for the way everyday electronics devices work. Currently, storing large amounts of data requires the use of a hard disk, which can be bulky and which needs access to a large battery power source. Spintronic microchips would mean that portable devices such as mobile phones and MP3 players would be able to store vast quantities of image, audio and video files, whilst remaining very small and light.

At five volumes and approximately, 2,500 pages, University of California, Riverside Electrical Engineering Professor Alexander Balandin’s handbook on nanotechnology is a big book about the tiniest of things.

The volumes were broken down into fundamental aspects of the field. The first volume deals with quantum dots, nanowires and nano-assemblies. The second volume covers nanofabrication and Nanoscale characterization, while volume three deals with spintronics and nanoelectronics. The fourth volume covers nanophotonics and optoelectronics. The final volume examines nanodevices and circuits.