Berlin 2018 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 68: Topological Insulators and Weyl Semimetals (joint session MA/TT)

TT 68.9: Talk

Wednesday, March 14, 2018, 17:15–17:30, EB 407

Impact of in-gap states on the magnetic stability/excitations of dopants in topological insulators — •Juba Bouaziz, Julen Ibanez-Azpiroz, Manuel dos Santos Dias, and Samir Lounis — Peter Grünberg Institut and Institute for Advanced Simulation, Forschungszentrum Jülich & JARA, D-52425 Jülich, Germany

Doping topological insulators with magnetic impurities breaks time reversal symmetry, leading to the prediction of a gap opening at the Dirac point when the magnetic moments are along the c-axis [1]. This could potentially functionalize the topological surface states by enabling control of the quantum anomalous Hall effect and dissipationless transport. Several investigations obtained conflicting results, generating a lot of controversy on this point. Since the orientation of the magnetic moments depends on their magnetic anisotropy energy, we use first-principles calculations to investigate isolated 3d and 4d transition metal impurities on the surfaces and in the bulk of Bi₂Te₃ and Bi₂Se₃. We explore the impact of impurity-induced in-gap states on the orientation of the magnetic moments, their dynamical spin-excitations and on the zero-point spin-fluctuations affecting the magnetic stability [2]. We propose to use scanning tunneling spectroscopy in the inelastic mode or in the electron spin resonance mode to verify our predictions.
– Funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (ERC-consolidator grant 681405 - DYNASORE).

[1] Y. L. Chen et al., Science. 329, 659 (2010).
[2] J. I. Azpiroz et al., Nano Lett. 16, 4305 (2016).