Perfect valley filter based on a topological phase in a disordered Sb monolayer heterostructure

Cheng, Shu-guang; Zhang, Ruizhi; Zhou, Jiao–Jiao; Jiang, Hua; Sun, Qing-Feng

doi:10.1103/physrevb.97.085420

Cited by 23 publications

(18 citation statements)

References 71 publications

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“…Moreover, the original Dirac cones at the K and K’ points are opened to form a complete photonic bandgap, resulting in the edge states at the interfaces of different valley Hall phases [ 23 , 24 , 25 ], which are immune to backscattering [ 28 , 29 ] caused by defects and acute light channels. In recent years, valley topological insulators (TIs) have been widely studied in optical, acoustic, and electronic systems, such as valley topological robust transport [ 18 , 19 , 20 ], topological photon routing [ 24 , 30 ], unidirectional light transport [ 24 ], valley topological edge state frequency tuning [ 13 ], valley topological acoustic wave group velocity modulation based on phononic crystals [ 13 ], and topological spin–valley filtering effects [ 31 , 32 ]. These studies have opened up unprecedented application opportunities for valley TIs in the fields of tunable acoustics, topological photonics, and the emerging field of nontrivial states.…”

Section: Introductionmentioning

confidence: 99%

Group Velocity Modulation and Light Field Focusing of the Edge States in Chirped Valley Graphene Plasmonic Metamaterials

Zhuo

Huang

et al. 2021

Nanomaterials

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The valley degree of freedom, like the spin degree of freedom in spintronics, is regarded as a new information carrier, promoting the emerging valley photonics. Although there exist topologically protected valley edge states which are immune to optical backscattering caused by defects and sharp edges at the inverse valley Hall phase interfaces composed of ordinary optical dielectric materials, the dispersion and the frequency range of the edge states cannot be tuned once the geometrical parameters of the materials are determined. In this paper, we propose a chirped valley graphene plasmonic metamaterial waveguide composed of the valley graphene plasmonic metamaterials (VGPMs) with regularly varying chemical potentials while keeping the geometrical parameters constant. Due to the excellent tunability of graphene, the proposed waveguide supports group velocity modulation and zero group velocity of the edge states, where the light field of different frequencies focuses at different specific locations. The proposed structures may find significant applications in the fields of slow light, micro–nano-optics, topological plasmonics, and on-chip light manipulation.

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Section: Introductionmentioning

confidence: 99%

Group Velocity Modulation and Light Field Focusing of the Edge States in Chirped Valley Graphene Plasmonic Metamaterials

Zhuo

Huang

et al. 2021

Nanomaterials

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“…Like the spin degree of freedom in spintronics devices [9][10][11], these inequivalent valleys or the valley degrees of freedom can also be used as information carriers to give birth to valleytronics [8,12,13]. Many unique transport phenomena can be realized by regulating these two degrees of freedom, such as fully spin-polarized current, the valley filter [14], and spin-valley filter [15][16][17][18][19].…”

Section: Introductionmentioning

confidence: 99%

Topological spin–valley filtering effects based on hybrid silicene-like nanoribbons

Yang

Zhang

et al. 2020

New J. Phys.

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Topological edge states have crucial applications in nano spintronics and valleytronics devices, while topological inner-edge states have seldom been extensively researched in this field. Based on the inner-edge states of the hybridized zigzag silicene-like nanoribbons, we investigate their transport properties. We propose two types of spin-valley filters. The first type can generate two different spin-valley polarized currents in output leads, respectively. The second type outputs the specific spin-valley polarized current in only one of the output leads. All these inner-edge states have the spin-valley-momentum locking property. These types of filters can switch the output spin-valley polarizations by modulating the external fields. Besides, we also find that the device size plays a crucial role in designing these spin-valley filters. Moreover, the local current distributions are calculated to visualize the detailed transport process and understand the mechanism. The mechanism lies that the spin-valley polarized current can nearly freely pass through the system with the same momentum, spin and valley degrees of freedom. The small reflection of the current results from the inter-valley scattering. In particular, we also consider the realistic (disorder) effects on the performance of these filters to ensure the robustness of our systems. We believe these spin-valley current filtering effects have potential applications in the future spintronics and valleytronics device designs.

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“…However, the weak spin-orbit coupling of these systems only leads to a tiny bulk gap with the order of a few meV, which limits the applications in the topological devices. Recently, the QSH effect is proposed in group-V monolayers (e.g., bismuthene [17][18][19][20] and antimonene [21][22][23][24] ). In these systems, the bulk gap can reach the same order of the atomic spin-orbit coupling strength of Bi and Sb.…”

Section: Introductionmentioning

confidence: 99%

Engineering a topological quantum dot device through planar magnetization in bismuthene

Zhou

Cheng

et al. 2019

Phys. Rev. B

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The discovery of quantum spin Hall materials with huge bulk gaps in experiment, such as bismuthene, provides a versatile platform for topological devices. We propose a topological quantum dot (QD) device in bismuthene ribbon in which two planar magnetization areas separate the sample into a QD and two leads. At zero temperature, peaks of differential conductance emerge, demonstrating the discrete energy levels from the confined topological edge states. The key parameters of the QD, the tunneling coupling strength with the leads and the discrete energy levels, can be controlled by the planar magnetization and the sample size. Specially, different from the conventional QD, we find that the angle between two planar magnetization orientations provides an effective way to manipulate the discrete energy levels. Combining the numerical calculation and the theoretical analysis, we identify that such manipulation originates from the unique quantum confinement effect of the topological edge states. Based on such mechanism, we find the spin transport properties of QDs can also be controlled.

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Perfect valley filter based on a topological phase in a disordered Sb monolayer heterostructure

Cited by 23 publications

References 71 publications

Group Velocity Modulation and Light Field Focusing of the Edge States in Chirped Valley Graphene Plasmonic Metamaterials

Group Velocity Modulation and Light Field Focusing of the Edge States in Chirped Valley Graphene Plasmonic Metamaterials

Topological spin–valley filtering effects based on hybrid silicene-like nanoribbons

Engineering a topological quantum dot device through planar magnetization in bismuthene

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