%0 Journal Article
%A Sessi, P.
%A Rüßmann, P.
%A Bathon, T.
%A Barla, A.
%A Kokh, K. A.
%A Tereshchenko, O. E.
%A Fauth, K.
%A Mahatha, S. K.
%A Valbuena, M. A.
%A Godey, S.
%A Glott, F.
%A Mugarza, A.
%A Gargiani, P.
%A Valvidares, M.
%A Long, N. H.
%A Carbone, C.
%A Mavropoulos, P.
%A Blügel, S.
%A Bode, M.
%T Superparamagnetism-induced mesoscopic electron focusing in topological insulators
%J Physical review / B
%V 94
%N 7
%@ 2469-9950
%C Woodbury, NY
%I Inst.
%M FZJ-2016-07606
%P 075137
%D 2016
%X 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.
%F PUB:(DE-HGF)16
%9 Journal Article
%U <Go to ISI:>//WOS:000381483700002
%R 10.1103/PhysRevB.94.075137
%U https://juser.fz-juelich.de/record/825129