  The intrinsic magnetic topological insulator MnBi2Te4 (MBT) has provided a
platform for the successful realization of exotic quantum phenomena. To broaden
the horizons of MBT-based material systems, we intercalate ferromagnetic MnTe
layers to construct the [(MBT)(MnTe)m]N superlattices by molecular beam
epitaxy. The effective incorporation of ferromagnetic spacers mediates the
anti-ferromagnetic interlayer coupling among the MBT layers through the
exchange spring effect at the MBT/MnTe hetero-interfaces. Moreover, the precise
control of the MnTe thickness enables the modulation of relative strengths
among the constituent magnetic orders, leading to tunable magnetoelectric
responses, while the superlattice periodicity serves as an additional tuning
parameter to tailor the spin configurations of the synthesized multi-layers.
Our results demonstrate the advantages of superlattice engineering for
optimizing the magnetic interactions in MBT-family systems, and the
ferromagnet-intercalated strategy opens up new avenues in magnetic topological
insulator structural design and spintronic applications.
