Helmholtz Association

Magnetic Monopoles in Spin Ice

Am Experimentierplatz des Berliner Forschungsreaktors durchleuchten Physiker die Proben mit Neutronen. Foto: HZB/A. Rouvière
Physicists screen probes with neutrons at the experimental area of the Berlin research reactor. Photo: HZB/A. Rouvière

So far, magnetic monopoles have not raised any attention in nature. In contrast to electric charges, magnetic “charges” principally occur only as dipoles with a north and a south pole. Therefore, the discovery of magnetic monopoles in autumn 2009 constituted a sensation. Indeed, Dr. Jonathan Morris, Bastian Klemke and Professor Dr. Alan Tennant from the HZB observed a fascinating phenomenon: At temperatures near absolute zero, they researched the magnetic structures within a dysprosium titanate crystal. This compound is marked by a special geometry as can be found also in frozen water. Whereas in water ice, the hydrogen atoms are located at the corners of tetrahedrons, in “spin ice” dysprosium ions take their place and spatially align their magnetic moments or spins. At around one degree Kelvin above absolute zero, these spins form long, intertwined chains, so-called spin spaghetti, which the researchers could observe by way of neutron radiation at the Berlin research reactor. They found that the ends of these spin spaghetti behaved like single magnetic monopoles under an external magnetic field. Tennant explains, that an individual chain of magnetic moments was a one-dimensional object in a three-dimensional space. As of a certain length, the ends of these chains can be considered to be free.

Actually, the now verified magnetic monopoles thus are not new particles, because they originate through the interaction of an enormous number of atoms within a special geometry. “Yet they behave like a new kind of particle”, says Tennant. And so they also allow new insights into nature.

Insights into Research: Structure of of Matter

A Look at the Cosmic Primeval Soup

Since March 2010, it operates according to routine – the Large Hadron Collider LHC in Geneva, the strongest accelerator of all times. Usually, it uses hydrogen nuclei (protons) to achieve new energy records. Yet as of autumn 2010, the 27 kilometre large ring is to collide the nuclei of lead atoms for the first time.

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Insights into Research: Structure of of Matter

Neutrino Hunt at the South Pole

It is the southern-most large-scale experiment of the world: “IceCube” is located at the South Pole and consists of around 5000 optical sensors, held on wire ropes and inserted up to 2.5 kilometres deep into the ice of the Antarctic.

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Einblicke in die Forschung: Struktur der Materie

Data at the End of the Tunnel

Just like Dr. Manuel Bibes and his colleagues from the French research organisation CNRS south of Paris, Dr. Sergio Valencia and Dr. Florian Kronast from the Helmholtz-Zentrum Berlin (HZB) für Materialien und Energie are classical basic researchers. And yet they show a way towards the development of fast starting computers with low energy consumption with their work on electric control of electron spins.

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Einblicke in die Forschung: Struktur der Materie

Flash Explores New States of Matter

Usually, it shimmers in a dull silver – simply typically aluminium. Yet given extreme circumstances, the light metal can become translucent, not for normal light, but for soft x-rays. This feature was discovered by an international team of physicists at the Research Centre DESY in Hamburg by way of the light source FLASH. Amongst other things, the result is of relevance for astrophysics and fusion research.

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Einblicke in die Forschung: Struktur der Materie

Heavy Elements

The hitherto heaviest, officially acknowledged chemical element has the atomic number 112 and was discovered at the GSI Helmholtz Centre for Heavy Ion Research in Darmstadt. Since February 2010, it at last has a name: Copernicium, chemical symbol “Cn”, named for the astronomer Nikolaus Kopernikus.

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09.01.2013