Tailoring the magnetic exchange interaction in MnBi2Te4 superlattices via the intercalation of ferromagnetic layers

The intrinsic magnetic topological insulator MnBi 2 Te 4 (MBT) provides a platform for the creation of exotic quantum phenomena. Novel properties can be created by modification of the MnBi 2 Te 4 framework, but the design of stable magnetic structures remains challenging. Here we report ferromagnet-intercalated MnBi 2 Te 4 superlattices with tunable magnetic exchange interactions. Using molecular beam epitaxy, we intercalate ferromagnetic MnTe layers into MnBi 2 Te 4 to create [(MBT)(MnTe) m ] N superlattices and examine their magnetic interaction properties using polarized neutron reflectometry and magnetoresistance measurements. Incorporation of the ferromagnetic spacer tunes the antiferromagnetic interlayer coupling of the MnBi 2 Te 4 layers through the exchange-spring effect at MnBi 2 Te 4 /MnTe hetero-interfaces. The MnTe thickness can be used to modulate the relative strengths of the ferromagnetic and antiferromagnetic order, and the superlattice periodicity can tailor the spin configurations of the synthesized multilayers. The magnetic exchange interaction of MnBi 2 Te 4 —an intrinsic magnetic topological insulator—can be tuned by intercalating ferromagnetic layers of MnTe.