TY  - JOUR
AU  - Sessi, P.
AU  - Rüßmann, P.
AU  - Bathon, T.
AU  - Barla, A.
AU  - Kokh, K. A.
AU  - Tereshchenko, O. E.
AU  - Fauth, K.
AU  - Mahatha, S. K.
AU  - Valbuena, M. A.
AU  - Godey, S.
AU  - Glott, F.
AU  - Mugarza, A.
AU  - Gargiani, P.
AU  - Valvidares, M.
AU  - Long, N. H.
AU  - Carbone, C.
AU  - Mavropoulos, P.
AU  - Blügel, S.
AU  - Bode, M.
TI  - Superparamagnetism-induced mesoscopic electron focusing in topological insulators
JO  - Physical review / B
VL  - 94
IS  - 7
SN  - 2469-9950
CY  - Woodbury, NY
PB  - Inst.
M1  - FZJ-2016-07606
SP  - 075137
PY  - 2016
AB  - 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.
LB  - PUB:(DE-HGF)16
UR  - <Go to ISI:>//WOS:000381483700002
DO  - DOI:10.1103/PhysRevB.94.075137
UR  - https://juser.fz-juelich.de/record/825129
ER  -