  Ne\'el skyrmions originate from interfacial Dzyaloshinskii Moriya interaction
(DMI). Recent studies have explored using ferromagnet to host Ne\'el skyrmions
for device applications. However, challenges remain to reduce the size of
skyrmion to near 10 nm. Amorphous rare-earth-transitional-metal ferrimagnets
are attractive alternative materials to obtain ultrasmall skyrmions at room
temperature. Their intrinsic perpendicular magnetic anisotropy and tunable
magnetization provides a favorable environment for skyrmion stability. In this
work, we employ atomistic stochastic Landau-Liftshitz-Gilbert (LLG) algorithm
to investigate skyrmions in GdFe within the interfacial DMI model. Despite the
rapid decay of DMI away from the interface, small skyrmions of near 10 nm are
found in thick ~ 5 nm amorphous GdFe film at 300K. We have also considered
three scenarios for the sign of DMI between Gd-Fe pair. It is revealed that
antiferromagnetic coupling in the ferrimagnet plays an important role in
enhancing the effect of interfacial DMI and to stabilize skyrmion. These
results show that ferrimagnets and antiferromagnets with intrinsic
antiferromagnetic couplings are appealing materials to host small skyrmions at
room temperature, which is crucial to improve density and energy efficiency in
skyrmion based devices.
