High-harmonic generation in Weyl semimetal β-WP2 crystals

Yang-Yang Lv; Jinlong Xu; Shuang Han; Chi Zhang; Yadong Han; Jian Zhou; Shu-Hua Yao; Xiao-Ping Liu; Ming-Hui Lu; Hongming Weng; Zhenda Xie; Y B Chen; Jianbo Hu; Yan-Feng Chen; Shining Zhu

doi:10.1038/s41467-021-26766-y

High-harmonic generation in Weyl semimetal β-WP₂ crystals

Nat Commun. 2021 Nov 8;12(1):6437. doi: 10.1038/s41467-021-26766-y.

Authors

Yang-Yang Lv^#¹, Jinlong Xu^#², Shuang Han¹, Chi Zhang¹, Yadong Han³, Jian Zhou¹, Shu-Hua Yao⁴, Xiao-Ping Liu⁵, Ming-Hui Lu¹, Hongming Weng⁶, Zhenda Xie⁷, Y B Chen⁸, Jianbo Hu³, Yan-Feng Chen¹, Shining Zhu¹

Affiliations

¹ National Laboratory of Solid State Microstructures, School of Physics, School of Electronic Science and Engineering, College of Engineering and Applied Sciences, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, 210093, Nanjing, China.
² National Laboratory of Solid State Microstructures, School of Physics, School of Electronic Science and Engineering, College of Engineering and Applied Sciences, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, 210093, Nanjing, China. longno.2@163.com.
³ Laboratory for Shock Wave and Detonation Physics, Institute of Fluid Physics, China Academy of Engineering Physics, 621900, Mianyang, China.
⁴ National Laboratory of Solid State Microstructures, School of Physics, School of Electronic Science and Engineering, College of Engineering and Applied Sciences, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, 210093, Nanjing, China. shyao@nju.edu.cn.
⁵ School of Physical Science and Technology, Shanghai Tech University, 201210, Shanghai, China.
⁶ Beijing National Laboratory for Condensed Matter Physics, Institute of Chinese Academy of Sciences, 100190, Beijing, China.
⁷ National Laboratory of Solid State Microstructures, School of Physics, School of Electronic Science and Engineering, College of Engineering and Applied Sciences, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, 210093, Nanjing, China. xiezhenda@nju.edu.cn.
⁸ National Laboratory of Solid State Microstructures, School of Physics, School of Electronic Science and Engineering, College of Engineering and Applied Sciences, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, 210093, Nanjing, China. ybchen@nju.edu.cn.

^# Contributed equally.

Abstract

As a quantum material, Weyl semimetal has a series of electronic-band-structure features, including Weyl points with left and right chirality and corresponding Berry curvature, which have been observed in experiments. These band-structure features also lead to some unique nonlinear properties, especially high-order harmonic generation (HHG) due to the dynamic process of electrons under strong laser excitation, which has remained unexplored previously. Herein, we obtain effective HHG in type-II Weyl semimetal β-WP₂ crystals, where both odd and even orders are observed, with spectra extending into the vacuum ultraviolet region (190 nm, 10th order), even under fairly low femtosecond laser intensity. In-depth studies have interpreted that odd-order harmonics come from the Bloch electron oscillation, while even orders are attributed to Bloch oscillations under the "spike-like" Berry curvature at Weyl points. With crystallographic orientation-dependent HHG spectra, we further quantitatively retrieved the electronic band structure and Berry curvature of β-WP₂. These findings may open the door for exploiting metallic/semimetallic states as solid platforms for deep ultraviolet radiation and offer an all-optical and pragmatic solution to characterize the complicated multiband electronic structure and Berry curvature of quantum topological materials.