Berlin 2015 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 39: Posters II (Topological insulators; Graphene; Spintronics and spin physics; Quantum information science)
HL 39.1: Poster
Dienstag, 17. März 2015, 14:00–20:00, Poster F
Magnetic and structural stability of topological-insulator / ferromagnet hybrid structures during thermal annealing procedures — •Michal Vališka1, Martin Vondráček2, Hubert Steiner3, Gunther Springholz3, Václav Holý1, Vladimír Sechovský1, and Jan Honolka2 — 1DCMP, Charles University, Prague, Czech Republic — 2IoP, Academy of Sciences of the Czech Republic, Prague, Czech Republic — 3HFP, Johannes Kepler Universität, Linz, Austria
Magnetic atoms in the vicinity of the topologically protected surface states (TTS) of 3D topological insulators could break time-reversal symmetry and open efficient spin-flip channels for backscattering processes. We have shown earlier that single magnetic adatom spins situated on Bi2Se3 surfaces randomly fluctuate at temperatures T∼4 K[1]. In order to achieve stable exchange fields, our present work focuses on MBE-grown heterostructures consisting of thin surface layers of pure Bi2Se3 and a buried, remanently magnetized Mn-doped layer. The heterostructure is sealed by a protective Se capping. We present an optimized Se capping and decapping procedure of Mn-doped samples under UHV conditions. Surface properties after decapping are controlled by PEEM and XPS measurements, and the TSS state is monitored in situ by k-PEEM. The important question of potential changes of the magnetic properties of Mn-doped layers (1-10%) due to diffusion effects during decapping at elevated temperatures is addressed via measurements of the bulk magnetization using SQUID.
[1] J. Honolka, et al., Physical Review Letters 108, 256811 (2012)