TY - JOUR
T1 - Synthetic Three-Dimensional Z × Z2 Topological Insulator in an Elastic Metacrystal
AU - Wang, Wei
AU - Chen, Ze Guo
AU - Ma, Guancong
N1 - Funding Information:
This work was supported by Hong Kong Research Grants Council (GRF 12302420, 12300419, ECS 22302718, CRF C6013-18G), National Natural Science Foundation of China Excellent Young Scientist Scheme (Hong Kong & Macau) (11922416) and Youth Program (11802256), and Hong Kong Baptist University (RC-SGT2/18-19/SCI/006).
Publisher Copyright:
© 2021 American Physical Society.
PY - 2021/11/19
Y1 - 2021/11/19
N2 - We report a three-dimensional (3D) topological insulator (TI) formed by stacking identical layers of Chern insulators in a hybrid real-synthetic space. By introducing staggered interlayer hopping that respects mirror symmetry, the bulk bands possess an additional Z2 topological invariant along the stacking dimension, which, together with the nontrivial Chern numbers, endows the system with a Z×Z2 topology. A 4-tuple topological index characterizes the system's bulk bands. Consequently, two distinct types of topological surface modes (TSMs) are found localized on different surfaces. Type-I TSMs are gapless and are protected by Chern numbers, whereas type-II gapped TSMs are protected by Z2 bulk polarization in the stacking direction. Remarkably, each type-II TSM band is also topologically nontrivial, giving rise to second-order topological hinge modes (THMs). Both types of TSMs and the THMs are experimentally observed in an elastic metacrystal.
AB - We report a three-dimensional (3D) topological insulator (TI) formed by stacking identical layers of Chern insulators in a hybrid real-synthetic space. By introducing staggered interlayer hopping that respects mirror symmetry, the bulk bands possess an additional Z2 topological invariant along the stacking dimension, which, together with the nontrivial Chern numbers, endows the system with a Z×Z2 topology. A 4-tuple topological index characterizes the system's bulk bands. Consequently, two distinct types of topological surface modes (TSMs) are found localized on different surfaces. Type-I TSMs are gapless and are protected by Chern numbers, whereas type-II gapped TSMs are protected by Z2 bulk polarization in the stacking direction. Remarkably, each type-II TSM band is also topologically nontrivial, giving rise to second-order topological hinge modes (THMs). Both types of TSMs and the THMs are experimentally observed in an elastic metacrystal.
UR - http://www.scopus.com/inward/record.url?scp=85119989304&partnerID=8YFLogxK
U2 - 10.1103/PhysRevLett.127.214302
DO - 10.1103/PhysRevLett.127.214302
M3 - Article
C2 - 34860114
AN - SCOPUS:85119989304
VL - 127
JO - Physical Review Letters
JF - Physical Review Letters
SN - 0031-9007
IS - 21
M1 - 214302
ER -