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nanotimes News in Brief

11-05 :: May/June 2011

Ferromagnetism plus Superconductivity // Researchers Discover a Rare Physical Phenomenon at Low Temperatures and High Magnetic Fields

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cientists from the Dresden High Magnetic Field Laboratory (HLD), Helmholtz-Zentrum Dres-

den Rossendorf (HZDR), and the TU Dresden, both Germany, were able to verify with an interme- tallic compound of bismuth and nickel that certain materials actually exhibit the two contrary proper- ties of superconductivity and ferromagnetism at the same time. A phenomenon that had only been demonstrated around the globe on a small number of materials and which might provide highly interesting technological opportunities in future.

Headed by Dr. Thomas Herrmannsdörfer, the team from the HZDR’s High Magnetic Field Laboratory (HLD) examined a material consisting of the ele- ments bismuth and nickel (Bi3

Ni) with a diameter of

only a few nanometers – which is unique since it has not been achieved elsewhere so far.

This was made possible through a new chemical synthesis procedure at low temperatures which had been developed at the TU Dresden under the lea- dership of Prof. Michael Ruck. The nanoscale size and the special form of the intermetallic compound – namely, tiny fibers – caused the physical proper- ties of the material, which is non-magnetic under normal conditions, to change so dramatically. This is a particularly impressive example of the excellent

opportunities modern nanotechnology can provide today, emphasizes Dr. Thomas Herrmannsdörfer. “It’s really surprising to which extend the properties of a substance can vary if one manages to reduce their size to the nanometer scale.”

There are numerous materials which become super- conducting at ultralow temperatures. However, this property competes with ferromagnetism which normally suppresses superconductivity. This does not happen with the analyzed compound: Here, the Dresden researchers discovered with their experi- ments in high magnetic fields and at ultralow tem- peratures that the nanostructured material exhibits completely different properties than larger-sized samples of the same material. What’s most surpri- sing: The compound is both ferromagnetic and superconducting at the same time.

It is, thus, one of those rarely known materials which exhibit this unusual and physically not yet completely understood combination. Perhaps bismuth-3-nickel features a special type of superconductivity, says Dr. Herrmannsdörfer. The physicist and doctoral can- didate Richard Skrotzki, who has just turned 25, is making a vital contribution to the research results and describes the phenomenon as “the bundling of contrary properties in a single strand.”