Tailoring exchange couplings in magnetic topological-insulator/antiferromagnet heterostructures

Magnetic topological insulators such as Cr-doped (Bi,Sb) 2 Te 3 provide a platform for the realization of versatile time-reversal symmetry-breaking physics. By constructing heterostructures exhibiting Néel order in an antiferromagnetic CrSb and ferromagnetic order in Cr-doped (Bi,Sb) 2 Te 3 , we realize emergent interfacial magnetic phenomena which can be tailored through artificial structural engineering. Through deliberate geometrical design of heterostructures and superlattices, we demonstrate the use of antiferromagnetic exchange coupling in manipulating the magnetic properties of magnetic topological insulators. Proximity effects are shown to induce an interfacial spin texture modulation and establish an effective long-range exchange coupling mediated by antiferromagnetism, which significantly enhances the magnetic ordering temperature in the superlattice. This work provides a new framework on integrating topological insulators with antiferromagnetic materials and unveils new avenues towards dissipationless topological antiferromagnetic spintronics. Heterostructures formed by the magnetic topological insulator Cr-doped (Bi,Sb) 2 Te and the antiferromagnet CrSb are shown to exhibit emergent interfacial magnetic phenomena that can be tuned with the heterostructure geometry.