Tuesday, August 14, 2012

"CHIPS: "IBM maps spin-helix semiconductors"

IBM and scientists at ETH Zurich for the first time have demonstrated a spin helix in a semiconductor, thereby synchronizing electrons to extends their spin lifetime of the electron by 30 times to over one nanosecond--the same time it takes for an existing 1 GHz processor to cycle: R. Colin Johnson

IBM scientist Gian Salis demonstrates how synchronizing electrons extends the spin lifetime thereby making spintronics feasible.

The first direct mapping of a persistent spin helix in a semiconductor has been demonstrated by IBM Researhc (Zurich). By extending the spin lifetime of electrons by 30-times to the cycle time of a 1GHz processor, the researchers were able to demonstrate the feasibility of using spin to store, transport and process information. IBM claims its discovery heralds a new class of magnetic-based transistors that use spin--instead of charge--resulting in more energy efficient semiconductors.

"The idea of a persistent spin helix was put forward by theoretical physicists in the group of professor Daniel Loss at the University of Basel [in 2003]," said IBM researcher Gian Salis. "Our direct experimental observation was enabled by both, the unique experimental set-up that allows for time-resolved imaging of spin polarization at low temperatures and high magnetic fields, as well as the excellent sample material produced by our collaborators at ETH Zurich."

Spintronics has been favored for the next generation of electronics, since individual electrons could then be used to store either ones or zeros depending on their spin orientation. However, researchers have not been able to demonstrate long-enough spin lifetimes to make the technique commercially feasible.

IBM scientists demonstrated spin lifetimes of over a nanosecond by using laser pulses to monitor spin orientation of thousands of electrons in a quantum well. By arranging their spins into a regular stripe-like pattern--called a persistent spin helix--the IBM scientists were able to synchronize electron spins and verify they stayed in sych over distances of over 10 microns, a distance that would allow logical operation to be performed.

The gallium arsenide (GaAs) material in which the persistent spn helix was demonstrated was produced by scientists at ETH Zurich. The experiment was performed at 40 degrees Kelvin (-387 F).

Funding was provided by the Swiss National Science Foundation, the National Center of Competence in Research (NCCR) Nanoscale Sciences and NCCR Quantum Science and Technology.
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