Activities
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topological transition on anisotropic hexagonal lattices and effective phonon model for the quantum hall transition
Andreas Sinner
Institut für Physik, Universität Augsburg, Germany
3 September 2020 Thu 4 pm
IBS Center for Theoretical Physics of Complex Systems (PCS), Administrative Office (B349), Theory Wing, 3rd floor
Expo-ro 55, Yuseong-gu, Daejeon, South Korea, 34126 Tel: +82-42-878-8633
The topology of the band structure, which is determined by the lattice symmetries, has a strong influence on the transport properties. We consider an anisotropic honeycomb lattice and study the effect of a continuously deformed band structure on the conductivity and optical properties. We find a strong suppression of the conductivity in one direction and increment by several orders in another which leand to a considerable change of optical properties.
We further study a gap generation in a two-dimensional Dirac fermion system which are coupled to in-plane phonons. At sufficiently strong electron-phonon interaction a gap appears in the spectrum of fermions. The structure of elementary excitations above the gap in the corresponding phase reveals the presence of scale invariant parity breaking terms which resemble Chern-Simons excitations. The Kubo formula yields quantized Hall plateaux.
In collaboration with Antonio Hill and Klaus Ziegler (University Augsburg, Germany), Phusit Nualpijit (Kasetsart University Thailand), Jirii Lozovik (Academy of Sciences of Russian Federation).
References:
New J. Phys. 13, 035023 (2011); EPL 119, 27001 (2017); PRB 97, 235411 (2018); PRB 93, 125112 (2016);
Ann. Phys. 400, 262 (2018); Ann. Phys. 418, 168199 (2020); Phys. Rev. Research 2, 033085 (2020).