Publication date: Oct 22, 2020
Rare earth ions typically exhibit larger magnetic moments than transition metal ions and thus promise the opening of a wider exchange gap in the Dirac surface states of topological insulators. Yet, in a recent photoemission study of Eu-doped Bi2Te3 films, the spectra remained gapless down to T=20K. Here, we scrutinize whether the conditions for a substantial gap formation in this system are present by combining spectroscopic and bulk characterization methods with theoretical calculations. For all studied Eu doping concentrations, our atomic multiplet analysis of the M4,5 x-ray absorption and magnetic circular dichroism spectra reveals a Eu2+ valence and confirms a large magnetic moment, consistent with a 4f7 8S7/2 ground state. At temperatures below 10K, bulk magnetometry indicates the onset of antiferromagnetic (AFM) ordering. This is in good agreement with density functional theory, which predicts AFM interactions between the Eu impurities. Our results support the notion that antiferromagnetism can coexist with topological surface states in rare-earth doped Bi2Te3 and call for spectroscopic studies in the kelvin range to look for novel quantum phenomena such as the quantum anomalous Hall effect.
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|3.6 KiB||Description of the dataset files|
|1.3 GiB||AiiDA export file of the dataset|
|206 Bytes||Table of J(r) values presented in the publication|
|14.8 KiB||Table of J(E) and DOS values presented in the publication|