Dresden 2017 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 4: Transport: Topological Insulators (jointly with DS, MA, HL, O)
MA 4.2: Vortrag
Montag, 20. März 2017, 09:45–10:00, HSZ 204
Low-temperature magnetotransport in Mn-doped Bi2Se3 topological insulators — V. Tkáč1, V. Komanicky2, R. Tarasenko1, M. Vališka1, V. Holý1, G. Springholz3, V. Sechovský1, and •J. Honolka4 — 1Department of Condensed Matter Physics, Faculty of Mathematics and Physics, Charles University, CZ — 2Institute of Physics, P. J. Šafárik University, SK — 3Institute of Semiconductor and Solid State Physics, Johannes Kepler University, AT — 4Institute of Physics, Academy of Sciences of the Czech Republic, CZ
Magnetic impurities can break the time-reversal symmetry of 3D topological insulators (TI), thereby opening an energy gap Δ at the Dirac point of a topological surface state with large consequences for transport properties in the thin film limit. In magnetotransport a transition from weak antilocalisation to weak localisation is expected, strongly dependent on contributions from possible coexisting 2D quantum well and bulk states. We present a low-T magnetotransport study (T = 0.3 K - 300 K, Bmax = 14 T) of MBE-grown Bi2Se3 films of 20 nm - 500 nm thickness with varying Mn concentrations up to 8% and Curie temperatures TC = 5 − 7 K [1,2]. The results are interpreted following mainly theory by Lu et al. [3] as a competition of quantum corrections to the conductivity σ (phase coherence length lφ∝ T−1/2 ∼ 50−150nm for pure Bi2Se3) and 2D e-e interaction corrections both in the ferro- and paramagnetic phase.
[1] M. Valiska et al., Appl. Phys. Lett. 108, 262402 (2016).
[2] R. Tarasenko et al., Physica B 481, 262 (2016).
[3] H.-Z. Lu et al., Phys. Rev. Lett. 112, 146601 (2014).