The regular lattice of 'magnetic skyrmons', extremely stable cycloidal vortex spin structures consist of 15 atoms in an atomic layer of iron on the surface of an iridium crystal. The discovery was made with the help of quantum mechanical calculations performed on supercomputers.
The newly discovered magnetic skyrmion lattice occurs in an atomically thin film on a surface. The diameter of the vortices is only a few atoms and is at least one order of magnitude smaller than previously known magnetic skyrmions. While it has previously been established that iron can sometimes form unusual magnetic structures, this is the first time researchers have discovered the almost square magnetic structure on the nanometre scale which is not really compatible with the hexagonal system of iron atoms.
To understand the spin structure and the exceptional symmetry breaking between magnetic and atomic order, the teams had to develop a model for the spin structure and carry out quantum mechanical calculations on supercomputers. These provided proof that stable magnetic skyrmions form on the metal surface. With the help of the model, the researchers could specify the precise spin structure in the iron film and identify it as a skyrmion lattice. The comparison with the experimental data provided ultimate proof.
The complex structure is caused by the interplay of various magnetic interactions and the skyrmions can only be induced by the 'four spin' interaction with the participation of four magnetic atoms.
According to the physicists, the new discovery paves the way for new applications in the field of spintronics.
