Observation of Distinct Bulk and Surface Chemical Environments in a Topological Insulator under Magnetic doping

TL;DR

This study reveals that magnetic doping in topological insulators like Bi2Te3 causes distinct chemical and electronic effects in surface and bulk regions, impacting their potential for spintronic applications.

Contribution

It provides spectroscopic evidence of different behaviors for surface and bulk magnetic doping in Bi2Te3, highlighting the importance of controlling doping processes for device development.

Findings

Bulk Mn doping induces dilute ferromagnetism and reduces the band gap.

Surface Fe deposition leads to iron telluride formation at low coverages.

Surface and bulk doping exhibit fundamentally different chemical and electronic behaviors.

Abstract

The influence of magnetic dopants on the electronic and chemical environments in topological insulators (TIs) is a key factor when considering possible spintronic applications based on topological surface state properties. Here we provide spectroscopic evidence for the presence of distinct chemical and electronic behavior for surface and bulk magnetic doping of Bi2Te3. The inclusion of Mn in the bulk of Bi2Te3 induces a genuine dilute ferromagnetic state, 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 formation of iron telluride already at coverages as low as 0.07 monolayer, as a consequence of the reactivity of the Te-rich surface. Our results identify the factors that need to be controlled in the realization of magnetic nanosystems and interfaces based on TIs.