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arXiv · 1904.02968

Nonlinear response in a non-centrosymmetric topological insulator

Zhou Li·Franco Nori
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Abstract

Nonlinear phenomena are inherent in most systems in nature. Second or higher-order harmonic generations, three-wave and four-wave mixing are typical phenomena in nonlinear optics. To obtain a nonzero signal for second-harmonic generation in the long-wavelength limit ($q\rightarrow0$), the breaking of inversion symmetry is required. In topological materials, a hexagonal warping term which breaks the rotation symmetry of the Fermi surface is observed by angular-resolved photo-emission spectroscopy (ARPES). If a gap opens (e.g., by doping with magnetic impurities) the inversion symmetry will be broken. Here we use a nonlinear response theory based on a generalized Kubo formula to explain the frequency up-conversion in topological materials.

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Zhou Li, Franco Nori. 2019-04-05. Nonlinear response in a non-centrosymmetric topological insulator. https://doi.org/10.1103/physrevb.99.155146

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