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Title: Chemical disorder in topological insulators: A route to magnetism tolerant topological surface states

Here, we show that the chemical inhomogeneity in ternary three-dimensional topological insulators preserves the topological spin texture of their surface states against a net surface magnetization. The spin texture is that of a Dirac cone with helical spin structure in the reciprocal space, which gives rise to spin-polarized and dissipation-less charge currents. Thanks to the nontrivial topology of the bulk electronic structure, this spin texture is robust against most types of surface defects. However, magnetic perturbations break the time-reversal symmetry, enabling magnetic scattering and loss of spin coherence of the charge carriers. This intrinsic incompatibility precludes the design of magnetoelectronic devices based on the coupling between magnetic materials and topological surface states. We demonstrate that the magnetization coming from individual Co atoms deposited on the surface can disrupt the spin coherence of the carriers in the archetypal topological insulator Bi 2Te 3, while in Bi 2Se 2Te the spin texture remains unperturbed. This is concluded from the observation of elastic backscattering events in quasiparticle interference patterns obtained by scanning tunneling spectroscopy. The mechanism responsible for the protection is investigated by energy resolved spectroscopy and ab initio calculations, and it is ascribed to the distorted adsorption geometry of localized magnetic momentsmore » due to Se–Te disorder, which suppresses the Co hybridization with the surface states.« less
Authors:
 [1] ; ORCiD logo [2] ;  [3] ; ORCiD logo [1] ;  [4] ;  [5] ; ORCiD logo [1] ;  [1] ; ORCiD logo [6] ; ORCiD logo [1]
  1. Univ. of Zaragoza, Zaragoza (Spain); Fundacion Instituto de Nanociencia de Aragon (FINA), Zaragoza (Spain)
  2. Donostia International Physics Center (DIPC), San Sebastian (Spain)
  3. Univ. of Zaragoza, Zaragoza (Spain)
  4. Ames Lab., Ames, IA (United States)
  5. Ames Lab. and Iowa State Univ., Ames, IA (United States)
  6. Donostia International Physics Center (DIPC), San Sebastian (Spain); IKERBASQUE, Basque Foundation for Science, Bilbao (Spain)
Publication Date:
Report Number(s):
IS-J-9336
Journal ID: ISSN 1530-6984; PII: 2358
Grant/Contract Number:
AC02-07CH11358
Type:
Accepted Manuscript
Journal Name:
Nano Letters
Additional Journal Information:
Journal Volume: 17; Journal Issue: 7; Journal ID: ISSN 1530-6984
Publisher:
American Chemical Society
Research Org:
Ames Lab., Ames, IA (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; 3D topological insulators; chemical disorder; magnetic atoms; quasiparticle-interference pattern; scanning tunneling microscopy
OSTI Identifier:
1371898