In situ x-ray absorption and photoelectron spectroscopy on epitaxial FexTe thin films with a wide range of Fe/Te compositions

FexTe thin films were prepared on SrTiO3 (001) substrates by molecular beam epitaxy in a well-ordered epitaxial layer-by-layer fashion. The composition of the films was varied by adjusting the Te flux in a Te-limited growth regime. Changes in the electronic structure were systematically studied using x-ray absorption spectroscopy at the Fe L2,3 and Te M4,5 edges and x-ray photoelectron spectroscopy of core levels and valence band. We found that FeTe with optimized composition (Fe/Te ratio ≈ 1) provides the sharpest spectral features, indicating that Fe1.00Te can be synthesized as a thin film, although it is not possible in bulk. Published by the American Physical Society 2024