Recently, a team from the Artificial Microstructure Physics Laboratory of the School of Physics and Optoelectronics, South China University of Technology (SCUT) has made important progress in two-dimensional topological phononic crystals, realizing acoustic spin aged insulators induced by pseudospin-orbit coupling. Acoustic spin-chern insulator induced by synthetic spin-orbit coupling with Spin conservation Breaking ( Synthesis of Spin Orbital-Coup-induced Acoustic Spin Aged Insulators with Non-conserved Spin) is published online in Nature Communications. Among them, South China University of Technology is the first signed unit, Associate professor Deng Weiyin and Professor Huang Xueqin are the co-first authors of the paper, and professor Li Feng and Professor Liu Zhengyou of Wuhan University are the co-corresponding authors. Co-authors of the paper include Associate Professor Jiuyang Lu, Professor Sebastian D. Huber of ETH, and Doctoral student Valerio Peri.
The discovery of topological insulators with physical gap and impotent gap edge states opens up a new direction for condensed matter physics. Broadly speaking, two-dimensional topological insulators can be divided into two categories. One is the one that breaks the symmetry of time inversion. For example, quantum (anomalous) Hall insulators have chiral edge states. The other class is one that preserves time inversion symmetry, such as quantum spin Hall insulators, which have helical edge states. The key to realize quantum spin hall insulators is the strong spin-orbit coupling of the system, which makes the wave function of the energy band have non-banal topological properties. Topological phases induced by spin-orbit coupling can be extended to three dimensions, i.e., three dimensional topological insulators. The topological properties of quantum spin Hall insulators can be described by Z2 index or spin number. In the case of spin conservation, the Z2 index is equivalent to the spin number. In fact, the definition of spin cycle number is independent of spin conservation and any symmetry, and has been used to describe topological and pseudospin topological insulators with time inversion symmetry breaking, resulting in the concept of spin cycle insulators. Spin-aged insulators have helical edge states, but whether they are incompetent gaps depends on the symmetry of the system and the microstructure of the sample boundary.
Previous studies on acoustic topological insulators have focused on limiting topological modes to the interface states at the domain walls between phases of phononic crystals. Although these studies are interesting in themselves, they have an important technical drawback: it is generally not possible to generate such modes at the edges of mononic crystal phases. In this work, acoustic spin insulation induced by pseudospin-orbit coupling was achieved (FIG. 1A), helical edge states propagating along the edges of mononic crystal phases were observed (FIG. 1B) and their robustness was verified (FIG. 1C), and spin reversal effects of edge states were observed in H-type samples (FIG. 1D).
Figure 1: Acoustic spin insulator
It is understood that the acoustic team in the Artificial Microstructure Physics Laboratory of the School of Physics and Opto-electronics mainly studies topological physics and novel transport operations in classical waves. He has published many articles in journals such as Nature Physics, Nature Materials, Nature Communications and Physical Review Letters with south China University of Technology as the first unit. This work is supported by the National Major Scientific Research Program of China, the National Natural Science Foundation of China, the Pearl River Talents Program of Guangdong Province, the Outstanding Youth Fund of Guangdong Province, and the Basic Research Fund of the Central Universities.
