Electron accumulation and charge neutrality level at the Eu/EuO interface




Gao, Lingyuan
Guo, Wei
Posadas, Agham
Demkov, Alexanader A.

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Using a combination of density functional theory and in situ X-ray photoelectron spectroscopy, we study the atomic and electronic structure of the Eu/EuO interface. Calculations predict that electrons transfer from Eu metal into EuO and induce an unexpected downward band bending at the interface. Accounting for spectral broadening and attenuation of the signal from subsurface layers, the calculated layer-resolved total density of states agrees well with experimental x-ray photoelectron spectroscopy in the valence band region. The total 4f spectrum contains contributions from both Eu and EuO, with the latter component significantly broadened as a result of band bending. This bending and charge transfer originate from Eu Fermi level pinning at the EuO charge neutrality level (CNL), which has been suggested to be located above the conduction band bottom.


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