Skyrmions are topologically protected field configurations with particle-like properties which play an important role in various fields of science ranging from elementary particles to condensed matter physics. We have discovered an atomic-scale magnetic skyrmion lattice as the spontaneous ground state of an ultra-thin film on a surface.

This intriguing non-collinear spin texture is observed in real-space exploiting the atomic resolution of spin-polarized scanning tunneling microscopy. By applying an extended Heisenberg model based on parameters determined from first-principles calculations we identified the interplay of Heisenberg exchange, four-spin and Dzyaloshinskii-Moriya interaction as its microscopic origin. The four-spin interaction - a higher order term beyond Heisenberg exchange - couples degenerate spin spirals and enforces a square-symmetry on the skyrmionic spin texture which is decoupled from the underlying hexagonal atomic lattice.

Figure (courtesy of M. Menzel, Univ. Hamburg):
Illustration of the atomic-scale magnetic skyrmion lattice discovered as the ground state of an Fe monolayer on the Ir(111) surface. Every cone denotes the spin of an Fe atom. This topologically non-trivial spin texture has been revealed by spin-polarized STM as shown by the transparent gray-scale image.

For more details refer to the following link:

Full article: Nature Physics 7, 713 (2011)

News & Views (Ch. Pfleiderer): Nature Physics 7, 673 (2011).

Gitter aus magnetischen Wirbeln, Physik in unserer Zeit 43, 6 (2012).

Press release of the CAU Kiel (2011): Lattice of magnetic vortices

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