Abstract
We present a nanoscale structural and density functional study of the Mn doped 3D topological insulator Bi2Te3. X-ray absorption near edge structure shows that Mn has valency of nominally 2+. Extended x-ray absorption fine structure spectroscopy in combination with electron energy loss spectroscopy (EELS) shows that Mn is a substitutional dopant of Bi and Te and also resides in the van der Waals gap between the quintuple layers of Bi2Te3. Combination of aberration-corrected scanning transmission electron microscopy and EELS shows that Mn substitution of Te occurs in film regions with increased Mn concentration. First-principles calculations show that the Mn dopants favor octahedral sites and are ferromagnetically coupled.
Highlights
Three-dimensional topological insulators (3D TIs) are a new class of materials with promising properties both for exploring fundamental physics and developing novel technological applications as spintronic devices.[1]
Mn doped Bi2Te3 crystals and thin films with doping concentrations of up to 10% were found to be ferromagnetic with Curie temperatures of around 10 K,15 it is not clear if ferromagnetism is due to secondary, undesirable Mn-containing phases or the homogeneous doping of Mn into the Bi2Te3 matrix, i.e., as a substitutional dopant
We show that the low Mn doping concentrations (∼2.5 at.%) in the Bi2Te3 preserved the structural integrity of the thin film
Summary
Three-dimensional topological insulators (3D TIs) are a new class of materials with promising properties both for exploring fundamental physics and developing novel technological applications as spintronic devices.[1]. By using real space atomic imaging and X-ray spectroscopy, we show that even at this low doping concentrations Mn is substitutionally incorporated into Bi2Te3, as well as in the van der Waals gap.
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