3D Acoustic Crystal

Non-orientable momentum-space topology

First realization of non-orientable Brillouin Klein space and half-turn space in 3D, enabling a new stacked weak Klein bottle insulator with self-collimated topological surface states.

Zhu, Zhenxiao · Linyun, Yang · Wu, Jien · Meng, Yan · Xi, Xiang · Yan, Bei · Jingming, Chen · Lu, Jiuyang · Huang, Xueqin · Deng, Weiyin · Shang, Ce · Shum, Perry Ping · Yang, Yihao · Chen, Hongsheng · Liu, Guigeng · Liu, Zhengyou · Gao, Zhen

Science Bulletin 2024

Advantages

Observed 3D momentum-space non-symmorphic symmetries (screw rotation and glide reflection)

Novel stacked weak Klein bottle insulator with nonzero Z2 topological invariant

Self-collimated topological surface states on opposite surfaces related by a nonlocal twist