  Epitaxial films of Co40Fe40B20 (further - CoFeB) were grown on Bi2Te3(001)
and Bi2Se3(001) substrates by laser molecular beam epitaxy (LMBE) technique at
200-400C. Bcc-type crystalline structure of CoFeB with (111) plane parallel to
(001) plane of Bi2Te3 was observed, in contrast to polycrystalline CoFeB film
formed on Bi2Se3(001) at RT using high-temperature seeding layer. Therefore,
structurally ordered ferromagnetic thin films were obtained on the topological
insulator surface for the first time. Using high energy electron diffraction
(RHEED) 3D reciprocal space mapping, epitaxial relations of main
crystallographic axes for the CoFeB/ Bi2Te3 heterostructure were revealed. MOKE
and AFM measurements showed the isotropic azimuthal in-plane behavior of
magnetization vector in CoFeB/ Bi2Te3, in contrast to 2nd order magnetic
anisotropy seen in CoFeB/Bi2Se3. XPS measurements showed more stable behavior
of CoFeB grown on Bi2Te3 to the oxidation, in compare to CoFeB grown on Bi2Se3.
XAS and XMCD measurements of both concerned nanostructures allowed calculation
of spin and orbital magnetic moments for Co and Fe. Additionally, crystalline
structure and XMCD response of the CoFeB/BiTeI and Co55Fe45/BiTeI systems were
studied, epitaxial relations of main crystallographic axes were found, and spin
and orbital magnetic moments were calculated.
