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TT: Fachverband Tiefe Temperaturen

TT 40: Topological Insulators (jointly with HL, MA)

TT 40.3: Talk

Wednesday, March 16, 2011, 17:15–17:30, HSZ 04

Does magnetism destroy the Dirac state in a topological insulator? — Arthur Ernst¹, •Jürgen Henk¹, Evgueni V. Chulkov², Igor V. Maznichenko³, and Ingrid Mertig³ — ¹Max Planck Institute of Microstructure Physics, Halle, Germany — ²Donostia International Physics Center, San Sebastian, Spain — ³Martin Luther University Halle-Wittenberg, Halle, Germany

A striking feature of topological insulators is that the Dirac states are protected by topology. However, how robust are these surface states against perturbations really? Given the prescribed spin structure of the Dirac state, one may ask whether magnetism destroys this state or — at least — modifies its spin-resolved dispersion.

To answer the above question we have investigated theoretically the topological insulator Bi₂Te₃(0001) by means of relativistic ab initio calculations. The Bi atoms in the topmost quintuple layer form a substitutional alloy with Mn (i. e. Bi_1−cMn_c) that is described within the coherent potential approximation. We find significant modificiations of the Dirac state in dependence of the Mn concentraction c and on the orientation of the Mn magnetic moments.