Large magnetic gap at the Dirac point in a Mn-induced Bi<sub>2</sub>Te<sub>3</sub> heterostructure
ORAL
Abstract
A magnetic gap at the Dirac point of topological insulators has so far never been observed directly. Here, we use low temperature ARPES to reveal the magnetic gap of Mn-doped Bi2Te3 films which is present only below TC of 10-12 K. Surprisingly, the gap is 5 times larger than predicted by density functional theory. We show that this enhancement is due to a remarkable structure modification induced by Mn doping. Instead of a disordered impurity system, it forms an alternating sequence of septuple and quintuple layer blocks, with Mn in the center of the septuple layers. Mn-doped Bi2Se3 forms a similar heterostructure, however, only a large, albeit nonmagnetic gap is formed. We explain both differences based on the higher spin-orbit interaction in Bi2Te3. The present findings provide crucial insights for pushing the lossless transport properties of topological insulators towards room temperature.
*Work was partially supported by CEDAMNF (CZ.02.1.01/0.0/0.0/15 003/0000358) of Czech ministry MSMT and by CEITEC Nano RI (MEYS CR, 20162019), by SPP1666 of Deutsche Forschungsgemeinschaft, and by Impuls- und Vernetzungsfonds der Helmholtz-Gemeinschaft
(Helmholtz-Russia Joint Research Group HRJRG-408 and Helmholtz Virtual Institute "New states of matter and their excitations").
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Presenters
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Oliver Rader
- Helmholtz-Zentrum Berlin