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arXiv · 2207.09888

High-pressure control of optical nonlinearity in the polar Weyl semimetal TaAs

Chen Li·Xiang Li·T. Deshpande·Xinwei Li·N. Nair·J. G. Analytis·D. M. Silevitch·T. F. Rosenbaum·D. Hsieh
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Abstract

The transition metal monopnictide family of Weyl semimetals recently has been shown to exhibit anomalously strong second-order optical nonlinearity, which is theoretically attributed to a highly asymmetric polarization distribution induced by their polar structure. We experimentally test this hypothesis by measuring optical second harmonic generation (SHG) from TaAs across a pressure-tuned polar-to-nonpolar structural phase transition. Despite the high-pressure structure remaining noncentrosymmetric, the SHG yield is reduced by more than 60 % by 20 GPa as compared to the ambient pressure value. By examining the pressure dependence of distinct groups of SHG susceptibility tensor elements, we find that the yield is primarily controlled by a single element that governs the response along the polar axis. Our results confirm a connection between the polar axis and the giant optical nonlinearity of Weyl semimetals and demonstrate pressure as a means to tune this effect $in$ $situ$.

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Chen Li, Xiang Li, T. Deshpande, Xinwei Li, N. Nair, J. G. Analytis, D. M. Silevitch, T. F. Rosenbaum, D. Hsieh. 2022-07-20. High-pressure control of optical nonlinearity in the polar Weyl semimetal TaAs. https://doi.org/10.1103/physrevb.106.014101

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