  We theoretically propose a new stabilization mechanism of a skyrmion crystal
(SkX) in a bilayer triangular lattice system consisting of the ferromagnetic
and the antiferromagnetic layers. By performing variational calculations and
Monte Carlo simulations in a complementary way, we find that a magnetic
frustration between the ferromagnetic and antiferromagnetic layers is a source
of a finite-Q spiral state and the SkX in the strong interlayer coupling
regime. We also show that the degree of frustration is related to the
interlayer exchange interaction. The stronger interlayer coupling tends to make
the effect of frustration larger, which results in the stabilization of the
SkX. The present results not only provide a way of engineering the SkX in the
ferromagnetic/antiferromagnetic domain and heterostructure but also imply the
possibility of the SkX based on interorbital frustration scenario.
