Multi-band acoustic topological insulator

Localization of edge state in acoustic topological insulators by curvature of space

“…In the past several decades, TIs have constituted an expanding research field in condensed matter, and the robust transport effect of boundary states against disorders has attracted intense interest in classical systems [7][8][9][10][11][12]. Inspired by these concepts, analogous topological optics/acoustic are becoming a hot notion throughout physics in a variety of frontier domains [13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29], such as one-way propagation [13,14], communications [15,16], and acoustic-noise reduction [17] and so on. Similar to the electrons propagating in a crystal, sound in the phononic crystal will also experience a periodic potential [18][19][20], and the physical performance can be delineated by the energy band structure, such as the concept of topology [21][22][23].…”

“…Inspired by these concepts, analogous topological optics/acoustic are becoming a hot notion throughout physics in a variety of frontier domains [13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29], such as one-way propagation [13,14], communications [15,16], and acoustic-noise reduction [17] and so on. Similar to the electrons propagating in a crystal, sound in the phononic crystal will also experience a periodic potential [18][19][20], and the physical performance can be delineated by the energy band structure, such as the concept of topology [21][22][23]. Topology derives from the winding of eigenmodes in momentum space and usually be characterized by the topological invariant, and each band has a topological invariant [24].…”

Frequency Band-Controllable Acoustic Topological Insulators Based on Local Dimensional Coordination

“…By opening the Dirac cone to generate two boundaries with different edge states to break the time-reversal symmetry and change the direction of its pseudospin, the quantum Hall-like effect is realized. In this case, the acoustic wave between these two boundaries can have topologically protected selective acoustic valley transmission properties. − And which band of acoustic waves for which the ATI has topologically protected edge state properties is mainly related to the position of the band gap opened by the double Dirac cone. The band with topology-protected edge state properties in ATI is called the effective band.…”

“…Therefore, many ATI researchers have been working on constructing different shapes of ATI structures to realize band gaps at different locations. − Some researchers have also tried to construct ATIs with wider band gaps . And other researchers tried to realize band gaps with different positions using one lattice cell to realize multiband ATI . The most effective method for the construction of a multiband is to combine known lattice cell shapes to obtain combinations with band gaps in which each lattice cell has to achieve multiband ATI.…”

“…29 researchers tried to realize band gaps with different positions using one lattice cell to realize multiband ATI 33 . 34 The most effective method for the construction of a multiband is to combine known lattice cell shapes to obtain combinations with band gaps in which each lattice cell has to achieve multiband ATI. Multiband acoustic topological insulators make a great contribution to the discovery of the potential value of acoustic topological insulators.…”