A study of the crystal structure of Co$_{40}$Fe$_{40}$B$_{20}$ epitaxial films on a Bi$_{2}$Te$_{3}$ topological insulator

Laser molecular-beam epitaxy has been used to form Co$_{40}$Fe$_{40}$B$_{20}$ layers on Bi$_{2}$Te$_{3}$ 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 Bi$_{2}$Te$_{3}$. 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.