Magnetic profile of proximity-coupled (Dy,Bi)2Te3/(Cr,Sb)2Te3 topological insulator heterostructures

Journal article

Magnetic topological insulators (TIs) are an ideal playground for the study of novel quantum phenomena building on time-reversal symmetry broken topological surface states. By combining different magnetic TIs in a heterostructure, their magnetic and electronic properties can be precisely tuned. Recently, we have combined high-moment Dy:Bi₂Te₃with high transition temperature Cr:Sb₂Te₃ in a superlattice, and found, using x-ray magnetic circular dichroism (XMCD), that long-range magnetic order can be introduced in the Dy:Bi₂Te₃ layers. Accompanying first-principles calculations indicated that the origin of the long-range magnetic order is a strong antiferromagnetic coupling between Dy and Cr magnetic moments at the interface extending over several layers. However, based on XMCD alone, which is either averaging over the entire thin film stack or is surface sensitive, this coupling scenario could not be fully confirmed. Here we use polarized neutron reflectometry (PNR), which is ideally suited for the detailed study of superlattices, to retrieve the magnetization in a layer- and interface-resolved way. We find that the magnetization is, in contrast to similar recent studies, homogeneous throughout the individual layers, with no apparent interfacial effects. This finding demonstrates that heterostructure engineering is a powerful way of controlling the magnetic properties of entire layers, with the effects of coupling reaching beyond the interface region.

Authors: Duffy, L; Steinke, N; Burn, D; Frisk, A; Lari, L

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: American Physical Society
• Journal: Physical Review B: Condensed matter and materials physics
• Volume: 100
• Issue: 5
• Article number: 054402
• Publication date: 2019-08-01
• Acceptance date: 2019-07-17
• DOI: 10.1103/PhysRevB.100.054402
• EISSN: 1550-235X
• ISSN: 1098-0121
• Keywords: multilayer thin films; magnetism; topological materials; solid-solid interfaces; neutron reflectometry; neutron scattering