  Creating materials that do not exist in nature can lead to breakthroughs in
science and technology. Magnetic skyrmions are topological excitations that
have attracted great attention recently for their potential applications in low
power, ultrahigh density memory. A major challenge has been to find materials
that meet the dual requirement of small skyrmions stable at room temperature.
Here we meet both these goals by developing epitaxial FeGe films with excess Fe
using atomic layer molecular beam epitaxy (MBE) far from thermal equilibrium.
Our novel atomic layer design permits the incorporation of 20% excess Fe while
maintaining a non-centrosymmetric crystal structure supported by theoretical
calculations and necessary for stabilizing skyrmions. We show that the Curie
temperature is well above room temperature, and that the skyrmions probed by
topological Hall effect have sizes down to 15 nm as imaged by Lorentz
transmission electron microscopy (LTEM) and magnetic force microscopy (MFM).
Our results illustrate new avenues for creating artificial materials tailored
at the atomic scale that can impact nanotechnology.
