Dortmund, Germany--Magneto-optical effects, which exploit the interaction between light and magnetic materials, have been relevant for fundamental research but up to now have rarely been used in applications. However, plasmons have opened up a new way to concentrate light at nanoscale dimensions, allowing plasmonic circuits to be built with electrical as well as optical control at this small scale. One ideal use for plasmonics would be to apply such optical control for processing data on hard drives, achieving heretofore impossible writing and scanning rates of up to one billion operations per second.
For this purpose, it should be possible to optically switch nanometer-sized magnetic-storage elements on such hard drives; optical excitation of plasmons could also be used. Physicists at Technische Universität Dortmund working with researcher Ilya Akimov, along with colleagues from Russia and India, have now succeeded in developing a procedure to merge magneto-optics and plasmonics. The results, realized in the laboratory of Experimental Physics II for the first time, are already so promising that their practical use in electronic components should be possible in the near future.
On the suggestion of 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 (a bismuth iron garnet film) transparent to red light. This gold grating has 100-nm-wide slits at intervals of a 500 nm; as a result, the gold grating itself, optically opaque without the slits, becomes highly transparent to red light. Moreover, depending on the magnetization of the ferromagnets, the transmission of the seies of layers can be drastically changed up to three orders of magnitude. Further improvements should be easily achieved through optimization of the investigated samples.
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