Quadratic Weyl semimetal and topological double negative refraction in phononic crystals

Authors：Zheng, Riyi; Yang, Yating; Deng, Weiyin^*; Lu, Jiuyang^*; Huang, Xueqin; Liu, Zhengyou

Source：Physical Review Applied, 2023, 20(4): 044035.

DOI：10.1103/PhysRevApplied.20.044035

• POINTS

We report the realization of an acoustic quadratic Weyl semimetal, which hosts a pair of quadratic Weyl points with opposite charges +/- 2 in the two lowest bands. The quadratic Weyl points, protected by C(4 )and time-reversal symmetries, have quadratic dispersions along the k(x )and k(y )directions and linear dispersion along the k(z) direction. Nonzero charges of the quadrative Weyl points give rise to the Fermi-arc boundary states. By constructing a domain wall, we further achieve the double negative refraction of the boundary acoustic waves without reflection in experiment. These results evidence the quadratic Weyl semimetal, and have potential applications in innovative acoustic devices.

• Institution
  武汉大学; 北京化工大学