Investigating the role of intermixed interface regions between complex oxides and van der Waals chalcogenides for magnetic proximity

The interactions between magnetic oxides and van der Waals topological insulators have great potential for tuning interfacial interactions and emergent properties. A promising example of such system is ferromagnetic (La,Sr)MnO3 coupled with topological insulating Bi2Te3 (BT). It has been discovered that in heterostructures between BT and magnetic Mn-based materials, the uncompensated Mn3+ d-orbital electrons effectively couple with the surface Dirac fermions of BT, leading to the creation of spin texture topological charges. However, recent studies on BT thin film growth reveal the challenges that are reflected in the formation of amorphous layer forming in the bottom-most layer of BT, as well as the intermixing of atomic species at the interface. The understanding of the inter-layer exchange and emergent properties is still limited. In part, this is due to the inherently weak signal coming from the interfacial phenomena, requiring state-of-the-art measurement techniques. More detailed interfacial study is critical to separately examine the effect in each layer and create the correct model. To that end, we aim to establish a thorough understanding of magnetic interactions at magnetic oxide/topological insulator material interfaces. This will be done by investigating the influence of BT layer on magnetic atoms of perovskites with spin polarized neutron reflectometry.