A Study of the Crystal Structure of Co₄₀Fe₄₀B₂₀ Epitaxial Films on a Bi₂Te₃ Topological Insulator

Laser molecular-beam epitaxy has been used to form Co₄₀Fe₄₀B₂₀ layers on Bi₂Te₃ topological insulator substrates, and their growth conditions have been studied. The possibility of growing epitaxial ferromagnetic layers on the surface of a topological insulator is demonstrated for the first time. The CoFeB layers have a body-centered cubic crystal structure with the (111) crystal plane parallel to the (0001) plane of Bi₂Te₃. 3D mapping in the reciprocal space of high-energy electron-diffraction patterns made it possible to determine the epitaxial relationships between the film and the substrate.