Design of GaAs-based valley phononic crystals with multiple complete phononic bandgaps at ultra-high frequency

Kim, Ingi; Arakawa, Yasuhiko; Iwamoto, Satoshi

doi:10.7567/1882-0786/ab0772

Cited by 21 publications

(18 citation statements)

References 55 publications

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“…In the simulations, the acoustic parameters for GaAs were density ρ = 5360 kg/m 3 , elastic constants C 11 = 111.8 GPa, C 12 = 53.8 GPa, C 44 = 59.4 GPa, and mechanical (acoustic) loss-factor Q −1 = 5 × 10 −4 . These acoustic parameters are experimentally valid from previous works so that defect and randomness in the structure and material property during device fabrication are considered in the calculation [25,26]. For Ni, they were density ρ = 8900 kg/m 3 , Young modulus E = 219 GPa and Poisson's ratio ν = 0.31.…”

supporting

confidence: 57%

Mode-sensitive magnetoelastic coupling in phononic-crystal magnomechanics

Hatanaka,

Yamaguchi

2021

Preprint

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supporting

confidence: 57%

Mode-sensitive magnetoelastic coupling in phononic-crystal magnomechanics

Hatanaka,

Yamaguchi

2021

Preprint

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“…However, numerical integration of the Berry curvature of our system shows that the anomalous integration numbers are about ±0.34 that are not limited to ±0.5. This may be caused by the strong spatial inversion symmetry breaking 9,30 . The strong spatial inversion symmetry breaking reflects the distribution of slowness curves and group velocity, which is related to the Berry curvature by…”

Section: Deviated Berry Curvature Of the Elastic Valley Metamaterialsmentioning

confidence: 99%

Valley anisotropy in elastic metamaterials

Kim

Iwamoto

et al. 2019

Phys. Rev. B

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Valley, as a new degree of freedom, raises the valleytronics in fundamental and applied science. The elastic analogs of valley states have been proposed by mimicking the symmetrical structure of either two-dimensional materials or photonic valley crystals. However, the asymmetrical valley construction remains unfulfilled. Here, we present the valley anisotropy by introducing asymmetrical design into elastic metamaterials. The elastic valley metamaterials are composed of bio-inspired hard spirals and soft materials. The anisotropic topological nature of valley is verified by asymmetrical distribution of the Berry curvature. We show the high tunability of the Berry curvature both in magnitude and sign enabled by our anisotropic valley metamaterials. Finally, we demonstrate the creation of valley topological insulators and show topologically protected propagation of transverse elastic waves relying on operating frequency. The proposed topological properties of elastic valley metamaterials pave the way to better understanding the valley topology and to creating a new type of topological insulators enabled by an additional valley degree of freedom. IntroductionElastic waves, possessing plenty of degree of freedoms (DOFs) including frequency, phase and polarization, have demonstrated tremendous promise in a variety of applications including target detection, information processing and biomedical imaging 1-4 . Recently, topology has been proposed as a new DOF in manipulating waves in both photonic and phononic systems, exhibiting remarkable impact not only on fundamental science such as condensed matter physics, but also on engineering applications such as low loss devices and waveguides 5-9 . In photonics, the photonic spin Hall effect has been achieved by taking advantage of spin DOF, which opens up an avenue of spin-dependent light transport and one-way spin transport 10-13 . In phononics, mechanical patterns and deformation have been employed as a new DOF to enable the elastic topological states 8,9,[14][15][16][17][18][19] .Recently, valley, the degenerate yet inequivalent energy extrema in momentum space, has emerged as a new dimension in manipulating waves in electronics, photonics and phononics 5,6,[20][21][22][23][24] . In graphene and transition metal dichalcogenides, valley-selective circular dichroism and valleyHall effect due to the long lifetime of valley polarization and non-zero Berry curvature have been studied for the promising applications in information carrier and storage 20,21,23,24 . As the concept of valley is introduced into the classic system, the photonic and phononic valley crystals are proposed, showing potential applications such as information processing via valley-dependent transportation 5,6,22 . However, existing designs of valley metamaterials are limited to the inherent spatial inversion symmetry of the physical system, where the typical Berry curvature distribution in the Brillouin zone follows Ω −# = Ω # . The valley metamaterials without spatial inversion symmetry have not yet bee...

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“…Moreover, most existing phononic QVH topological insulators operate only in a single frequency band, [ 16–22 ] and thus cannot be used for multiband applications such as multiband communications, multiband filters, and multiband subwavelength resonators. For large‐scale multifunctional topological phononic circuits, multiband phononic QVH topological insulators have been proposed theoretically [ 27 ] but are yet to be demonstrated experimentally in nano‐electromechanical systems.…”

Section: Figurementioning

confidence: 99%

Experimental Demonstration of Dual‐Band Nano‐Electromechanical Valley‐Hall Topological Metamaterials

Sun

2021

Advanced Materials

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Suppression of undesired backscattering of very‐high‐frequency elastic signals has been considered as a grand challenge in integrated phononic circuits. Originating from condensed‐matter physics, valley‐Hall topological insulators provide an intriguing strategy to overcome this challenge. To date, phononic valley‐Hall topological insulators have been demonstrated only in bulk acoustic and mechanical systems operating at relatively low frequencies. Here, an integrated nano‐electromechanical valley‐Hall topological insulator operating in the very‐high‐frequency regime is experimentally realized. Valley kink states that are backscattering‐immune against sharp bends and exhibit the “valley‐momentum locking” effect simultaneously in the fundamental (≈60 MHz) and second‐order (≈120 MHz) frequency bands are demonstrated. It is further shown that the propagation directions of these dual‐band valley kink states are always locked to their valley pseudospins. The results not only enable various applications in very‐high‐frequency integrated phononic circuits with enhanced robustness and capacity, but also open the door to experimental exploration of mechanical nonlinearities, particularly those involving the fundamental and second‐order frequencies, in topologically nontrivial nanostructures.

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Design of GaAs-based valley phononic crystals with multiple complete phononic bandgaps at ultra-high frequency

Cited by 21 publications

References 55 publications

Mode-sensitive magnetoelastic coupling in phononic-crystal magnomechanics

Mode-sensitive magnetoelastic coupling in phononic-crystal magnomechanics

Valley anisotropy in elastic metamaterials

Experimental Demonstration of Dual‐Band Nano‐Electromechanical Valley‐Hall Topological Metamaterials

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