Giant anisotropic nonlinear optical response in transition metal monopnictide Weyl semimetals

By Liang Wu, S. Patankar, T. Morimoto, N. Nair, E. Thewalt, A. Little, J. Analytis, J. E. Moore, Joseph Orenstein. Nature Physics, 2016

402 citations recorded by the source corpus.

An optical second-harmonic generation study of a series of transition metal monopnictide Weyl semimetals reveals a giant, anisotropic nonlinear optical response in these systems. Although Weyl fermions have proven elusive in high-energy physics, their existence as emergent quasiparticles has been predicted in certain crystalline solids in which either inversion or time-reversal symmetry is broken1,2,3,4. Recently they have been observed in transition metal monopnictides (TMMPs) such as TaAs, a class of noncentrosymmetric materials that heretofore received only limited attention5,6,7. The question that arises now is whether these materials will exhibit novel, enhanced, or technologically applicable electronic properties. The TMMPs are polar metals, a rare subset of inversion-breaking crystals that would allow spontaneous polarization, were it not screened by conduction electrons8,9,10. Despite the absence of spontaneous polarization, polar metals can exhibit other signatures of inversion-symmetry breaking, most notably second-order nonlinear optical polarizability, χ(2), leading to phenomena such as optical rectification and second-harmonic generation (SHG). Here we report measurements of SHG that reveal a giant, anisotropic χ(2) in the TMMPs TaAs, TaP and NbAs. With the fundamental and second-harmonic fields oriented parallel to the polar axis, the value of χ(2) is larger by almost one order of magnitude than its value in the archetypal electro-optic materials GaAs11 and ZnTe12, and in fact larger than reported in any crystal to date.

Subfields: Atomic and Molecular Physics, and Optics, Electronic, Optical and Magnetic Materials, Materials Chemistry

View Paper: https://www.semanticscholar.org/paper/692342f1edacc330ec091fe65eec3074f1d70e8b

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Citations in the corpus

Light control with Weyl semimetals (2022, background): “For example, photonic applications include compact optical isolators and circulators [6, 7, 8], orbital angular momentum detectors [9, 10], higher-order harmonic generation [11, 12, 13], and nonreciprocal thermal emitters [14, 15, 16] among many others.”
Topological Semimetals from First Principles (2018, background): “The breaking of P symmetry in nonmagnetic Weyl semimetals suggests that they may have interesting nonlinear optical properties, such as second harmonic generation and shift current, and these nonlinear optical responses have recently attracted much recent attention (106, 107, 108, 109, 110, 111).”
Weyl and Dirac semimetals in three-dimensional solids (2017, background): “And we have noted above the WSM systems TaAs, TaP and NbAs have the largest ever recorded SHG χ(2) coefficient (Wu et al., 2017).”