Structural engineering of La_0.7Sr_0.3MnO₃ thin films - towards magnetic oxide-van der Waals heterostructures

Quantum materials gain an increasing interest in the field of electronics research. One exciting opportunity is heterostructures of oxides and van der Waals materials exhibiting unique combined properties and emergent interfacial properties. Here, the first step is to ensure high-quality interfaces and the proper connectivity between inherently different crystal structures. In this work, we focus on structural engineering of ferromagnetic La_0.7Sr_0.3MnO₃ (LSMO) as hexagonal oxide layer. Our hypothesis is that exposing hexagonal symmetry along the (111) direction promotes connectivity to the hexagonal structure of dichalcogenide.

LSMO thin films are deposited by pulsed laser deposition (PLD) directly onto different substrates, i.e., (111)-oriented SrTiO₃ (STO) and muscovite mica, studying the effect on the structural and magnetic properties. AFM reveals the surface roughness and topography, showing a grain-like structure of LSMO grown on mica and step-terrace growth on STO, respectively. In addition to the different surface morphology, XRD measurements reveal the film on mica to be polycrystalline and the film on STO to be epitaxial. Most importantly for heterostructure engineering, hexagonal surface structure is achieved, which is crucial for depositing, e.g., Bi₂Te₃. With this, the research enables tuning interfacial magnetism via growth control of the oxide.