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Forschungszentrum Jülich - Research in Jülich 2_2013

16 Research in Jülich 2|2013 The Ernst Ruska-Centre (ER-C) is home to the most powerful electron microscopes worldwide, which pro- vide very exact images of the arrangement of atoms in materials. The researchers headed by Prof. Rafal Dunin- Borkowski will also use the devices for other purposes in future. They will make visible tiny magnetic fields in- side nanoparticles with unprecedented clarity. This will benefit information technology and other fields. Hot on the Trail of Nanomagnets I n 1831, the famous English scientist Michael Faraday was the first to demonstrate what was to become a standard experiment for generations of school students in their physics classes. Faraday placed a piece of paper on top of a magnet and poured iron filings on it. As if by magic, these filings formed a pattern of lines on the paper – proof of the existence of magnetic field lines. Prof. Rafal Dunin-Borkowski, director at Prof. Rafal Dunin-Borkowski is exploring the magnetism of nanoparticles with the help of electron holography. with a diameter of no more than 180 mil- lionths of a millimetre (nanometres). UNIQUE POSSIBILITIES Dunin-Borkowski and other researchers took this image with an electron microscope. The scientists used a special type of electron microscopy referred to as electron holography (see image ‘How electron holography works’). “Although this method opens up unique possibilities for exploring the magnetic properties of nanomaterials, it is only used by a handful of research groups worldwide,” says Dunin-Borkowski. This is all the more surprising given that the magnetism in nanometre dimensions is decisive for the function of materials that are used, for example, in medicine, for catalysis, and waste water treatment. “However, being able to measure and understand magnetic fields in materials on the nanometre scale is important in particular for information technologies of the future,” says Dunin-Borkowski. the Ernst Ruska-Centre and at Jülich’s Peter Grünberg Institute (PGI) is, in some way, following in Faraday’s foot- steps. He likes to show visitors an image that is very similar to that of a bar mag- net with field lines. And indeed it shows a magnetic field pattern. However, what’s really interesting about this im- age is that the field is not produced by an object that’s visible to the naked eye, but by an iron crystal in a carbon tube

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