  Skyrmions and antiskyrmions are topologically protected spin structures with
opposite topological charge. Particularly in coexisting phases, these two types
of magnetic quasi-particles may show fascinating physics and potential for
spintronic devices. While skyrmions are observed in a wide range of materials,
until now antiskyrmions were exclusive to materials with D2d symmetry. In this
work, we show first and second-order antiskyrmions stabilized by magnetic
dipole-dipole interaction in Fe/Gd-based multilayers. We modify the magnetic
properties of the multilayers by Ir insertion layers. Using Lorentz
transmission electron microscopy imaging, we observe coexisting antiskyrmions,
Bloch skyrmions, and type-2 bubbles and determine the range of material
properties and magnetic fields where the different spin objects form and
dissipate. We perform micromagnetic simulations to obtain more insight into the
studied system and conclude that the reduction of saturation magnetization and
uniaxial anisotropy leads to the existence of this zoo of different spin
objects and that they are primarily stabilized by dipolar interaction.
