Dresden 2017 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 16: Transport: Topological Phases (jointly with DS, MA, HL, O)
TT 16.2: Talk
Monday, March 20, 2017, 15:15–15:30, HSZ 304
Sign reversal of the quantized topological Hall effect in skyrmion crystals — •Börge Göbel1, Alexander Mook1, Jürgen Henk2, and Ingrid Mertig1,2 — 1Max-Planck-Institut für Mikrostrukturphysik, D-06120 Halle — 2Institut für Physik, Martin-Luther-Universität, D-06120 Halle
The topological Hall effect (THE) of electrons [1] is the hallmark of a skyrmion crystal phase [2]. It can be understood either by coupling of the electrons’ spin to the local magnetic texture (Zeeman interaction) or by coupling of the electrons’ charge to the emergent field generated by the texture (Peierls substitution).
Here, we study the THE on a triangular lattice, addressing band structure, Hall conductivity, and topological surface states. In this system, the THE is quantized and the transverse conductivity changes sign if the Fermi energy crosses a van Hove singularity. By mapping the THE to a quantum Hall effect (QHE) on a lattice [3], we assign this prominent feature to the cyclotron mass of electron orbits, that is, when constant-energy cuts of the band structure change from electron to hole pockets. Based on this picture, we derive an approximate rule which allows to determine the energy dependence of the topological Hall conductivity in any two-dimensional lattice.
[1] K. Hamamoto et al., Phys. Rev. B 92, 115417 (2015)
[2] S. Mühlbauer et al., Science 323, 915 (2009)
[3] Y. Hatsugai et al., Phys. Rev. B 74, 205414 (2006)