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Giant second-harmonic generation in Weyl semimetals

Nonlinear optical response of a Weyl semimetal. Berry curvature in the kxky plane showing singularities at the Weyl nodes.

Scientific Achievement
Discovered that the Weyl semimetals, TaAs, NbAs, and TaP, have the largest nonlinear optical response of any known crystal.

Significance and Impact
Understanding the origin of giant optical nonlinearity in Weyl semimetals will stimulate development of theoretical tools for computing optical response functions in bandstructures with Berry curvature.

Research Details

  • Nonlinear susceptibility was measured by detecting light reflected at λ = 400 nm stimulated by absorption of a sub-picosecond optical pulse at 800 nm.
  • Absolute susceptibility was determined by comparison with "standard candle" crystals ZnTe and GaAs.

Liang Wu, S. Patankar, T. Morimoto, N. L. Nair, E. Thewalt, A. Little, J. G. Analytis, J. E. Moore, J. Orenstein, Nature Physics (2016) doi:10.1038/nphys3969