June 2008

IBM and the ETH Zürich University have agreed to jointly build a laboratory for nanotechnology research. The research activities aim at technologies for the post-CMOS era such as carbon-based materials, nano photonics, spintronics, nanowires and tribology.

The lab will have a 90$ million investment. About one third will go to purchase equipment. The work will begin in Spring 2009, and the activities will start in 2011, and planned to last at least 10 years.

The researchers were experimenting with ferromagnet/semiconductor (FM/SC) structures, which are key building blocks for semiconductor spintronic devices (microelectronic devices that perform logic operations using the spin of electrons). The FM/SC structure is sandwich-like in appearance, with the ferromagnet and semiconductor serving as microscopically thin slices between which lies a thinner still insulator made of a few atomic layers of magnesium oxide (MgO).

The researchers found that by simply altering the thickness of the MgO interface they were able to control which kinds of electrons, identified by spin, traveled from the semiconductor, through the interface, to the ferromagnet.

Read more here (Eurekalert) 

Researchers at the RIKEN Advanced Science Institute (formerly the Frontier Research System) in Wako and the University of Tokyo have completed an important study into the effects that temperature can have on spintronic devices. Spintronics relies on the effective transport of ‘spin-polarized’ currents, in which electrons all have the same spin. Spin-polarized currents flow well in magnetic materials, but when they enter non-magnetic materials the electrons begin to lose their spin polarization in a process called spin-flip scattering. The length scale over which the electrons remain polarized, called the spin diffusion length, is particularly important for fabricating devices.

Spin-flip scattering is known to occur in two different ways. At high temperatures, most of the scattering is caused by electrons interacting with ‘waves of heat’ called phonons. Otherwise scattering is caused by impurities, defects and boundaries in the material.

To investigate the effects of temperature on spin-flip scattering, the researchers fabricated a ‘lateral spin valve’ consisting of two magnetic electrodes that inject a spin-polarized current through a copper wire. The distance between electrodes was altered in order to observe the spin diffusion length of the copper at different temperatures.

The researchers found that the spin diffusion length of the copper increased as temperature was decreased. This was expected, because the phonon scattering decreases with temperature. However, there was an unexpected maximum at around 30 K (-243.15 °C), below which the spin diffusion length decreased again.
The researchers explained this effect by considering the wire surfaces, which are oxidized by the surrounding air and cause strong spin-flip scattering. At very low temperatures, the polarized electrons travel further on average, so they are more likely to collide with the wire surfaces. This explanation was verified by tests with different thicknesses of wire, showing that thinner wires with greater surface-area-to-volume ratio experience a greater level of scattering at low temperatures.

Read more here (NanoWerk) 

Commonly used industrial dyes hold the key to advancing the new science of 'spintronics', say researchers working on a new a £2.5 million study.

The new Basic Technology grant awarded by the Engineering and Physical Sciences Research Council will support research into the magnetic properties of metal atoms found in industrial dyes such as Metal Phthalocyanine (MPc), a blue dye used in clothing. The team from the London Centre for Nanotechnology - a joint venture between Imperial College London and University College London - and the University of Warwick believes that finding ways to control and exploit these molecules will allow spintronics to be applied in new ways.

In order to advance spintronics, materials which combine both magnetic and semiconducting properties need to be found. The researchers believe that MPc, which is an organic semiconductor, holds the answer, and now aim to exploit the spin inherent in its metal atoms. Previous research carried out by this team has already demonstrated that spins in MPc can interact and these interactions can be switched – such switching is the first step towards use in information storage and logic operations.

The organic semiconductors to be used by the team for spintronics are very similar to those successfully used in solar cells and OLEDs, and which are leading the way into cheap 'plastic electronics'. This means that the benefits of organic semiconductors will be spread to more components of everyday electronics products such as computers and mobile telephones.