This title appears in the Scientific Report : 2016 

Superparamagnetism-induced mesoscopic electron focusing in topological insulators
Sessi, P. (Corresponding author)
Rüßmann, P. / Bathon, T. / Barla, A. / Kokh, K. A. / Tereshchenko, O. E. / Fauth, K. / Mahatha, S. K. / Valbuena, M. A. / Godey, S. / Glott, F. / Mugarza, A. / Gargiani, P. / Valvidares, M. / Long, N. H. / Carbone, C. / Mavropoulos, P. / Blügel, S. / Bode, M.
Quanten-Theorie der Materialien; IAS-1
Quanten-Theorie der Materialien; PGI-1
Physical review / B, 94 (2016) 7, S. 075137
Woodbury, NY Inst. 2016
Journal Article
Scattering of topologically protected states off defects in topological insulators
Controlling Configuration-Based Phenomena
Controlling Spin-Based Phenomena
Please use the identifier: in citations.
Please use the identifier: in citations.
Recently it has been shown that surface magnetic doping of topological insulators induces backscattering of Dirac states which are usually protected by time-reversal symmetry [Sessi et al., Nat. Commun. 5, 5349 (2014)]. Here we report on quasiparticle interference measurements where, by improved Fermi level tuning, strongly focused interference patterns on surface Mn-doped Bi2Te3 could be directly observed by means of scanning tunneling microscopy at 4 K. Ab initio and model calculations reveal that their mesoscopic coherence relies on two prerequisites: (i) a hexagonal Fermi surface with large parallel segments (nesting) and (ii) magnetic dopants which couple to a high-spin state. Indeed, x-ray magnetic circular dichroism shows superparamagnetism even at very dilute Mn concentrations. Our findings provide evidence of strongly anisotropic Dirac-fermion-mediated interactions and demonstrate how spin information can be transmitted over long distances, allowing the design of experiments and devices based on coherent quantum effects in topological insulators.