Electron spin memory
doi:10.1038/nindia.2010.170 Published online 30 November 2010
Through computer-based simulation studies, researchers have shown that a molecular system comprising cobalt and benzene adsorbed onto a gold surface displays unique behaviour in response to an external electric field.
The spin of an electron generally points either 'up' or 'down' in relation to a magnetic field. Electron spin in a molecular system, however, can give rise to an effect known as spin filtering. Such a molecular spin filter has the potential to bring memory and logic functionalities onto the same chip.
The researchers considered a simple cobalt–benzene–cobalt system with gold electrodes attached to both sides. They studied this system under the influence of a static electric field of up to 1 V.
The molecular system created two spin channels in response to the electric field. One of the channels allowed current to pass through while the other did not, thus producing the effect of a spin filter. This is the first example in which the spin filter action comes from the outer electrons of cobalt instead of its low-lying orbitals.
Electron spin, like the flow of charge, can also be used to carry information in a device. Unlike charge states, which are easily destroyed by scattering or collision with other charges, spin has long coherence.
"Molecular spin filters are therefore the most promising candidate for quantum computing device fabrication, high-density information storage and magnetic sensors," says lead researcher Swapan Chakrabarti.
The authors of this works are from: Department of Physics, JIS College of Engineering, Kalyani, Nadia and the Department of Chemistry, University of Calcutta, Kolkata, India.