The valley filter efficiency of monolayer graphene and bilayer graphene line defect model

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

doi:10.1088/1367-2630/18/10/103024

Cited by 35 publications

(44 citation statements)

References 48 publications

(105 reference statements)

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“…Moreover, it was shown that the broken inversion symmetry results in the valley-dependent optical selection rule, which can be used to selectively excite carriers in the K or −K valley via right or left circularly polarized light, respectively 10,11 . Valley polarization can also be achieved in monolayer [12][13][14][15] and bilayer 15 graphene systems with barriers. In addition, proposals exploiting strain that induces pseudomagnetic fields acting oppositely in the two valleys 16,17 together with artificially induced carrier mass and spin-orbit coupling 18 have been put forward.…”

Section: Introductionmentioning

confidence: 99%

Switchable valley filter based on a graphene p−n junction in a magnetic field

et al. 2017

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Low-energy excitations in graphene exhibit relativistic properties due to the linear dispersion relation close to the Dirac points in the first Brillouin zone. Two of the Dirac points located at opposite corners of the first Brillouin zone can be chosen as inequivalent, representing a new valley degree of freedom, in addition to the charge and spin of an electron. Using the valley degree of freedom to encode information has attracted significant interest, both theoretically and experimentally, and gave rise to the field of valleytronics. We study a graphene p-n junction in a uniform out-of-plane magnetic field as a platform to generate and controllably manipulate the valley polarization of electrons. We show that by tuning the external potential giving rise to the p-n junction we can switch the current from one valley polarization to the other. We also consider the effect of different types of edge terminations and present a setup, where we can partition an incoming valley-unpolarized current into two branches of valley-polarized currents. The branching ratio can be chosen by changing the location of the p-n junction using a gate.

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Section: Introductionmentioning

confidence: 99%

Switchable valley filter based on a graphene p−n junction in a magnetic field

et al. 2017

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“…15,21,25,26 Interestingly, it is recently noted that inter-valley scattering can provide a useful resource for valleytronics, besides its well anticipated role in depolarizing valley. 26 In 1D systems, it is shown that inter-valley scattering by disorders can realize a distinct valleytronic functionality, the valley source, where upon passing charge current, valley currents are pumped in both the forward and backward directions, with a net outward valley flux (c.f.…”

Section: -25mentioning

confidence: 99%

Switchable valley functionalities of an n − n ⁻ − n junction in 2D crystals

Yao

2017

2D Mater.

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We show that an n − n − − n junction in 2D semiconductors can flexibly realize two basic valleytronic functions, i.e. valley filter and valley source, with gate controlled switchability between the two. Upon carrier flux passing through the junction, the valley filter and valley source functions are enabled respectively by intra-and inter-valley scatterings, and the two functions dominate respectively at small and large band-offset between the n and n − regions. It can be generally shown that, the valley filter effect has an angular dependent polarity and vanishes under angular integration, by the same constraint from time-reversal symmetry that leads to its absence in one-dimension. These findings are demonstrated for monolayer transition metal dichalcogenides and graphene using tight-binding calculations. We further show that junction along chiral directions can concentrate the valley pump in an angular interval largely separated from the bias direction, allowing efficient havest of valley polarization in a cross-bar device.

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“…They hybridized SiNRs with different topological phases and found the topological valley edge states appeared at the interface between two different topological insulator phases. We have to mention that the valley edge states, also known as the kink states in graphene systems [27,28] or photonic crystals [29,30]. However, the definition of kink states are narrower than the inner-edge states.…”

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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The valley filter efficiency of monolayer graphene and bilayer graphene line defect model

Cited by 35 publications

References 48 publications

Switchable valley filter based on a graphene p−n junction in a magnetic field

Switchable valley filter based on a graphene p−n junction in a magnetic field

Switchable valley functionalities of an n − n ⁻ − n junction in 2D crystals

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

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The valley filter efficiency of monolayer graphene and bilayer graphene line defect model

Cited by 35 publications

References 48 publications

Switchable valley filter based on a graphene p−n junction in a magnetic field

Switchable valley filter based on a graphene p−n junction in a magnetic field

Switchable valley functionalities of an n − n − − n junction in 2D crystals

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

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Switchable valley functionalities of an n − n ⁻ − n junction in 2D crystals