Molecular beam epitaxy of antiferromagnetic (MnBi_2Te_4)(Bi_2Te_3) thin films on BaF_2 (111)

摘要

The layered van der Waals compounds (MnBi_2Te_4)(Bi_2Te_3) were recently established as the first intrinsic magnetic topological insulators. We report a study on the epitaxial growth of (MnBi_2Te_4)_m(Bi_2Te_3)_n films based on the co-deposition of MnTe and Bi_2Te_3 on BaF_2 (111) substrates. X-ray diffraction and scanning transmission electron microscopy evidence the formation of multilayers of stacked MnBi_2Te_4 septuple layers and Bi_2Te_3 quintuple layers with a predominance of MnBi_2Te_4. The elemental composition and morphology of the films is further characterized by x-ray photoemission spectroscopy and atomic force microscopy. X-ray magnetic circular and linear dichroism spectra are comparable to those obtained for MnBi_2Te_4 single crystals and confirm antiferromagnetic order in the films.