The heat which occurs in tiny computer processors might soon be no longer useless or even a problem. On the contrary: It could be used to switch these processors more easily or to store data more efficiently! These are two of the several potential applications made possible by a discovery made at the Physikalisch-Technische Bundesanstalt (PTB). This so-called "thermoelectronic voltage" may well be very interesting - mainly for the use of nano-junctions, i.e. small components based on magnetic tunnel structures. The results obtained by the researchers have been published in the current issue of the renowned specialised journal Physical Review Letters.
Today, magnetic tunnel structures already occur in various areas of information technology. They are used, for example, as magnetic storage cells in non-volatile magnetic memory chips (the so-called "MRAMs" - Magnetic Random Access Memories) or as highly sensitive magnetic sensors to read out the data stored on hard disks. The new effect discovered at PTB within the scope of a research collaboration with Bielefeld University and the Singulus company could, in the future, add a new application to the existing ones: monitoring and controlling thermoelectric voltages and currents in highly integrated electronic circuits.
Magnetic tunnel structures consist of two magnetic layers separated only by a thin insulation layer of approx. 1 nm - the so-called "tunnel barrier". The magnetic orientation of the two layers inside the tunnel structure has a great influence on its electrical properties: if the magnetic moments of the two layers are parallel to each other, the resistance is low; if, on the contrary, they are opposed to each other, the resistance is high. The change in the resistance when switching the magnetisation can amount to more than 100 %. It is therefore possible to control the electric current flowing through the magnetic tunnel structure efficiently by simply switching the magnetisation.
Contact: Dr. Hans Werner Schumacher, Department 2.5 "Semiconductor Physics and Magnetism", Tel. +49 (0)531 592-2500, e-mail: firstname.lastname@example.org
Scientific publication: Liebing, N.; Serrano-Guisan, S.; Rott, K.; Reiss, G.; Langer, J.; Ocker, B.; Schumacher, H.W.: Tunneling magneto power in magnetic tunnel junction nanopillars. Phys. Rev. Lett. 107, 177201 (2011), prl.aps.org/abstract/PRL/v107/i17/e177201