Topological aspects of nonlinear excitonic processes in noncentrosymmetric crystals

Takahiro Morimoto; Naoto Nagaosa

doi:10.1103/physrevb.94.035117

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arXiv · 1512.00549

Topological aspects of nonlinear excitonic processes in noncentrosymmetric crystals

Takahiro Morimoto·Naoto Nagaosa

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Abstract

We study excitonic processes second order in the electric fields in noncentrosymmetric crystals. We derive formulas for shift current and second harmonic generation produced by exciton creation, by using the Floquet formalism combined with the Keldysh Green's function method. It is shown that (i) the steady dc shift current flows by exciton creation without dissociation into free carriers and (ii) second harmonic generation is enhanced at the exciton resonance. The obtained formulas clarify topological aspects of these second order excitonic processes which are described by Berry connections of the relevant valence and conduction bands.

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Takahiro Morimoto, Naoto Nagaosa. 2016-07-08. Topological aspects of nonlinear excitonic processes in noncentrosymmetric crystals. https://doi.org/10.1103/physrevb.94.035117

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