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Special seminars TRR80


11.10.2018 4:15 p.m., room: S-288
Prof. Dr. Hiroshi Yasuoka (Max-Planck-Institut für chemische Physik fester Stoffe, Dresden)
Weyl fermion excitations in transition metal pnictides explored by 93Nb NMR and 181Ta NQR
30.10.2018 4 p.m., room: S-288
Prof. Dr. Markus J. Aichhorn (TU Graz)
Strong Correlations and Spin-Orbit Coupling: Models and Materials
17.1.2019 2:30 p.m., room: S-403
Prof. Dr. Sándor Bordács (BUTE, Budapest)
Detection of antiferromagnetic domains by optical magnetoelectric effect
29.1.2019 4 p.m., room: S-288
Dr. Maia G. Vergniory (Donostia International Physics Center, Ikerbasque)
Higher Order Topological Insulators from Elementary Band Representations Theory
22.2.2019 10:30 a.m., room: S-288
Prof. Dr. Andrei Pimenov (Institut für Festkörperphysik, TU Wien)
Topological insulators: quantized Faraday rotation and the band structure

Topological insulators are materials which are insulating in the bulk and which reveal conducting surface states. The electrodynamics of topological insulators is described by modified Maxwell’s equations, which contain additional terms that couple an electric field to a magnetization, such that the coupling coefficient is quantized in odd multiples of e2 ⁄ 2hc per surface. The new term leads to universal values of Faraday rotation angle equal to the fine structure constant 𝛼 ≈ 1/137 radian when a linearly polarized terahertz radiation passes through a topological insulator. This regime is obtained in high magnetic field and in the quantum regime.

In weak external magnetic fields the quasi-classical approximation is realized and a series of cyclotron resonances is observed in the terahertz frequency range. From the analysis of these experiments the band structure of topological insulator HgTe can be obtained both for 2D and 3D configurations. Therefore, the magneto-optical technique provide an experimental method to test the band structure calculations of topological insulators based on quantum wells.

19.3.2019 4 p.m., room: S-403
Prof. Dr. Sergey Artyukhin (Italian Institute of Technology (IIT), Genoa)
Sliding domain walls in ferroelectrics and multiferroics
22.3.2019 2 p.m., room: S-288
Dr. F. Sebastián Bergeret (Materials Physics Center, CSIC, Spain)
Universal correspondence between edge spin accumulation and equilibrium spin-currents in nanowires