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Foeschungszentrum Jülich - Research in Jülich 1_2013

Research in Jülich 1|20134 I n the journal Nature Materials, an international team of researchers including physicists from Forschungszen- trum Jülich published an article on how magnetism emerges at low temperatures in one of the most impor- tant semiconductors. The scientists studied a magnetic semiconductor known as gallium manganese arsenide us- ing a method they recently developed. In the most power- ful particle accelerator worldwide, SPring-8 in Harima Sci- ence Garden City in Japan, they bombarded the material with photons. This allowed them to observe the proper- ties of electrons deep inside the material. They discov- ered that on the atomic level, the magnetism has two competing causes – a result that, for the first time, exper- imentally confirmed theoretical predictions made in the last few years. The electrical properties of semiconductors form the basis of modern information technology. If it were possi- ble to also exploit the magnetic properties of electrons in semiconductors, information could be transported in a more energy-efficient manner. :: Magnetic Semiconduc- tors Under Fire First place in Europe, fifth place world- wide: that’s our new supercomputer JUQUEEN’s current ranking in the TOP500 list of the fastest supercom- puters in the world – a result that makes us proud. JUQUEEN is the first supercomputer in Europe to reach a peak perfor- mance of 5.9 petaflops, which equates to almost six quadrillion (1015 ) arithmetic operations per second. For our research, this means that we are now able to perform more complex simulations and can look for- ward to even more precise and informative results. One of the projects that will benefit from the new pos- sibilities opened up by JUQUEEN is the simulation of the human brain. This is the objective of the Human Brain Project, on which we are working in cooperation with international partners and which has just been provided with generous funding by the EU as one of its flagships. However, research on novel materials and quantum physics, as well as energy and climate research will also profit from the improved computing power. In addition, JUQUEEN is also among the most energy-efficient supercomputers in the world. In this issue of Research in Jülich, we are pleased to introduce you to this ‘Queen of Computers’. Fur- ther topics include merging stars, a new type of bat- tery based on silicon and air, and the decision-making behaviour of managers. Be prepared to be surprised by our research! I hope that this issue makes for interesting reading. Yours sincerely, Prof. Achim Bachem Chairman of the Board of Directors of Forschungszentrum Jülich :: EDITORIAL The neurons in the brain exchange information via a gigantic network of connections known as synapses. To date it was unclear how and when these relay stations form and disappear. Neuroscientists from the Bernstein Center Freiburg and the Institute of Neuroscience and Medicine at Forschungszentrum Jülich recently presented a new ex- planation in the journal PLOS Com- putational Biology. Using theoreti- cal models, they discovered a pre- viously unknown mechanism. If two neurons are already connected by several links, they form an addi- tional connection when exchanging information. However, this new synapse only continues to exists if the two neurons are active in the right order. Otherwise it will begin to atrophy. :: Cultivating Contacts in the Brain Information in the brain is relayed from synapse to synapse. High-energy photons (green arrow) release electrons from inside the sample (red arrow). Measuring these electrons provides information on the magnetic properties of the sample.

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