Research in SANMAG

Magnetism of Nanowires Driven by Novel Even-Odd Effects

Storing increasing amounts of data on increasingly small spaces is one of the prerequisites for further progress in information technology. A magnetic effect, which makes magnetic switches and logic elements conceivable on an atomic scale, has been discovered by theoretical scientists from the Research Center of Juelich in Germany. The results of their computer simulations mean that nanowires made of transition metals could be suitable for transporting and storing magnetic information. 

Lounis, Dederichs and Bluegel discovered a kind of domino effect in rows of individual manganese atoms on a nickel surface. They noticed that the magnetic configuration of these nanowires differed depending on their length. Astonishingly, only one atom more or one less makes a drastic difference. When the number of atoms is odd, the orientation of the magnetic moments is antiparallel, and when the number is even, they line up in a toppled compromise position between parallel and antiparallel. Adding an atom at the end of the nanowire or taking one away simultaneously changes the magnetic configuration of the entire cluster. Just like a row of dominoes, the magnetic moments topple over. However, this is where the analogy ends because the effect can be completely reversed in contrast to dominoes that have toppled over.

This new quantum mechanical effect, which holds for long stretches of at least 100 atoms, has been discovered using a refined version of density functional theory. The authors hopes that it will be proven experimentally in the near future.

To read the full article please visit, Physical Review Letters,  101, 107204 (2008)

This research was carried out in the frame of the SANMAG (Self-Assembled Nanoscale Magnetic Networks) Project.