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Posted: May 10, 2011
Optical control of magnetic effects at the nanoscale
(Nanowerk News) Magneto-optical effects, which exploit the interaction between light and magnetic materials, have only been relevant for fundamental research and up to now rarely used for applications. Plasmons – electronic excitations in metals with dimensions at the nanoscale – recently opened a new way to concentrate light at nanoscale. This allows plasmonic circuits to be built with electrical as well as optical control at this dimension scale.
It would be ideal to apply such optical control for processing data on hard drives. This way writing and scanning frequencies of up to one billion operations per second, impossible so far, can be achieved. For this purpose it should be possible to optically switch the magnetic storage elements of a nanometer size on such hard drives. Optical excitation of plasmons could also be used here.
Physicists at TU Dortmund around Dr. Ilya Akimov and colleagues from Russia and India now succeeded in developing a procedure to merge magneto-optics and plasmonics ("Enhanced magneto-optical effects in magnetoplasmonic crystals"). The effects which were realized in the laboratory of Experimental Physics II for the first time are already that promising, that their application in electronic components should be possible in the next future.
On the suggestion of Dr. Vladimir Belotelov and his colleagues from Moscow State University, Russian samples were produced at the Tata-Institute of Fundamental Research in Mumbai / India where a gold grating was applied to a ferromagnetic material (bismuth iron garnet film) transparent for red light. This gold grating has 100 nanometers wide slits at an interval of a half micrometer. Thus, the gold grating, optically opaque without the slits, becomes highly transparent for red light. Moreover, depending on the magnetization of the ferromagnets, the transmission of this layer-series can be drastically changed up to one thousand times as often as reported before, as shown by the experiments carried out at TU Dortmund by Dr. Ilya Akimov and his colleagues. Further improvements should be easily achieved through optimization of the investigated samples.