Resonant photoemission study of Eu1−xGdxTe layers

Resonant photoemission study of electronic structure of molecular beam epitaxy grown Eu1−xGdxTe layers without and with cover protected layer of Te were performed using synchrotron radiation. The analysis of the valence band and shallow core levels spectra of the clean surface of Eu1−xGdxTe obtained in situ under UHV conditions showed the existence of Eu2+ and Eu3+ ions in the layers. The trivalent europium ions mostly are located at the surface and its amount strongly depends on sample surface preparation conditions. The prolonged annealing of Eu1−xGdxTe layers covered with protected layer of Te leads to formation of clean surface of the sample not changing the stoichiometry of it and without the accumulation of Eu3+ ions at the surface region.