The influence of magnetic dopants on the electronic and chemical environmentsin topological insulators (TIs) is a key factor when considering possiblespintronic applications based on topological surface state properties. Here weprovide spectroscopic evidence for the presence of distinct chemical andelectronic behavior for surface and bulk magnetic doping of Bi2Te3. Theinclusion of Mn in the bulk of Bi2Te3 induces a genuine dilute ferromagneticstate, with reduction of the bulk band gap as the Mn content is increased.Deposition of Fe on the Bi2Te3 surface, on the other hand, favors the formationof iron telluride already at coverages as low as 0.07 monolayer, as aconsequence of the reactivity of the Te-rich surface. Our results identify thefactors that need to be controlled in the realization of magnetic nanosystemsand interfaces based on TIs.
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