Magnetic skyrmions are prime candidates for the next
generation
of spintronic devices. Skyrmions and other topological magnetic structures
are known to be stabilized by the Dzyaloshinskii-Moriya interaction
(DMI) that occurs when the inversion symmetry is broken in thin films.
Here, we show by first-principles calculations and atomistic spin
dynamics simulations that metastable skyrmionic states can also be
found in nominally symmetric multilayered systems. We demonstrate
that this is correlated with the large enhancement of the DMI strength
due to the presence of local defects. In particular, we find that
metastable skyrmions can occur in Pd/Co/Pd multilayers without external
magnetic fields and can be stable even near room temperature conditions.
Our theoretical findings corroborate with magnetic force microscopy
images and X-ray magnetic circular dichroism measurements and highlight
the possibility of tuning the intensity of DMI by using interdiffusion
at thin film interfaces.