Magnetic and electrical properties of 3D topological insulator Bi2Te3 doped with Mn (Conference Presentation)

Recent theoretical predictions confirmed by experimental observations provided evidence that there exist materials which behave as insulators in the bulk but possess gapless, spin-momentum-locked, linearly dispersed states on the surface. They are called topological insulators (TI). The conducting surface states of TIs are immune to localization as long as the disorder potential does not violate time reversal symmetry. One way to break the time reversal symmetry is to introduce magnetic dopants into the TIs that can induce ferromagnetism and open the surface energy gap. Opening a gap at the topological surface may result in exotic quantum phenomena including magnetoelectric effect and quantized anomalous Hall effect. In this work, we studied magnetic and electrical properties of the bismuth telluride doped with 2 % of Mn atoms. Ferromagnetic resonance (FMR) measurements show two resonance lines with different spin relaxation times, which we assigned to Mn2+ ions located at different lattice sites. Hall resistance measurements reveal that below 15 K the curve becomes hysteretic that is typical for ferromagnetic conductors. Hall as well as FMR demonstrate that the Curie temperature of the studied sample is between 10 and 15 K. Furthermore, the electric transport measurements reveal n-type conductivity indicating that Mn atoms may occupy interstitial position in van der Waals gaps. Magnetoresistance data show weak localization effect which may be one of the signature of the gap opening on the topological surface, other possible explanations related to the crystal structure will be also discussed. We would like to acknowledge National Science Center, Poland, grant no 2016/21/B/ST3/02565.