Zero-field magnetic skyrmions in exchange-biased ferromagnetic-antiferromagnetic bilayers.

We report on the stabilization of ferromagnetic skyrmions in zero external magnetic fields, in
exchange-biased systems composed of ferromagnetic-antiferromagnetic (FM-AFM) bilayers. By per-
forming atomistic spin dynamics simulations, we study cases of compensated, uncompensated, and
partly uncompensated FM-AFM interfaces, and investigate the impact of important parameters such
as temperature, inter-plane exchange interaction, Dzyaloshinskii-Moria interaction, and magnetic
anisotropy on the skyrmions appearance and stability. The model with an uncompensated FM-AFM
interface leads to the stabilization of individual skyrmions and skyrmion lattices in the FM layer,
caused by the effective field from the AFM instead of an external magnetic field. Similarly, in the
case of a fully compensated FM-AFM interface, we show that FM skyrmions can be stabilized. We
also demonstrate that accounting of interface roughness leads to the stabilization of skyrmions both in
compensated and uncompensated interfaces. Moreover, in bilayers with a rough interface, skyrmions
in the FM layer are observed for a wide range of exchange interaction values through the FM-AFM
interface, and the chirality of the skyrmions depends critically on the exchange interaction.

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