Valley filtering in strain-induced 
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 quantum dots

Filusch, Alexander; Bishop, A. R.; Saxena, Avadh; Wellein, Gerhard; Fehske, Holger

doi:10.1103/physrevb.103.165114

Cited by 18 publications

(7 citation statements)

References 37 publications

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“…Figures 2 (a), (b) and (c) show the transmission T of electrons originating from the left lead moving to the right lead and their valley polarization τ [K] for graphene (α = 0), the intermediate 1/ √ 3-T3 lattice, and the dice lattice (α = 1), respectively. The main feature of the static bump is an almost complete valley polarization of the transmitted electrons stemming from the excitation to α-dependent strain-induced Landau levels leading to 'flower-like' LDOS patterns inside the deformed region [10,11,13,54]. One of the main caveats is the reduction in valley polarization of the output current with increasing energy since the main contribution comes from the lowest energy band [13].…”

Section: Resultsmentioning

confidence: 99%

“…Recently, elastic deformations in α-T 3 structures have been shown to induce PMFs that efficiently valley filter incoming electrons by excitation to α-dependent (pseudo) Landau levels [54,55]. When the out-of-plane deformations also oscillate in time, complementary PEFs are induced that drive electrons of opposite valleys in different directions.…”

Section: Introductionmentioning

confidence: 99%

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Tunable valley filtering in dynamically strained $α$-$\mathcal{T}_3$ lattices

Filusch¹,

Fehske²

2022

Preprint

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Mechanical deformations in α-T3 lattices induce local pseudomagnetic fields of opposite directionality for different valleys. When this strain is equipped with a dynamical drive, it generates a complementary valley-asymmetric pseudoelectric field which is expected to accelerate electrons. We propose that by combining these effects by a time-dependent nonuniform strain, tunable valley filtering devices can be engineered that extend beyond the static capabilities. We demonstrate this by implementing an oscillating Gaussian bump centered in a four-terminal Hall bar α-T3 setup and calculating the induced pseudoelectromagnetic fields analytically. Within a recursive Floquet Green-function scheme, we determine the time-averaged transmission and valley polarization, as well as the spatial distributions of the local density of states and current density. As a result of the periodic drive, we detect novel energy regimes with highly valley-polarized transmission, depending on α. Analyzing the spatial profiles of the time-averaged local density of states and current density we can relate these regimes to the pseudoelectromagnetic fields in the setup. By means of the driving frequency, we can manipulate the valley-polarized states, which might be advantageous for future device applications.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Tunable valley filtering in dynamically strained $α$-$\mathcal{T}_3$ lattices

Filusch¹,

Fehske²

2022

Preprint

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“…The chiral flat band has been shown to be stable against perturbations of the transfer amplitude like strain, magnetic fields, or boundary conditions due to the bipartite nature of the lattice and plays only a secondary role for the singleparticle transport properties [19,[34][35][36][37][38][39][40], but its geometry and composition have not yet been discussed in detail.…”

Section: Introductionmentioning

confidence: 99%

Singular Flat Bands in the Modified Haldane-Dice Model

Filusch¹,

Fehske²

2023

Preprint

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“…A number of properties of finite size dice lattice quantum dots were studied in recent years. Among them are the description of distributions of edge currents in quantum dots [31], prediction appearance of Majorana corner states in the presence of Rashba coupling [32], size dependence of Landau levels formed in the ring made of α − T 3 lattice [33], analysis of the role of atomic effects in narrow zigzag ribbons [34], valley filtering [35,36] and dynamical formation of bound states by external driving [37] in α − T 3 lattice quantum dots. The formation of pseudo-Landau levels in nonuniform strain for triangular shaped quantum dots was discussed in [38].…”

Section: Introductionmentioning

confidence: 99%

Size effects on atomic collapse in the dice lattice

Oriekhov,

Voronov

2023

J. Phys.: Condens. Matter

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We study the role of size effects on atomic collapse of charged impurity in the flat band system. The tight-binding simulations are made for the dice lattice with circular quantum dot shapes. It is shown that the mixing of in-gap edge states with bound states in impurity potential leads to increasing the critical charge value. This effect, together with enhancement of gap due to spatial quantization, makes it more difficult to observe the dive-into-continuum phenomenon in small quantum dots. At the same time, we show that if in-gap states are filled, the resonant tunneling to bound state in the impurity potential might occur at much smaller charge, which demonstrates non-monotonous dependence with the size of sample lattice. In addition, we study the possibility of creating supercritical localized potential well on different sublattices, and show that it is possible only on rim sites, but not on hub site. The predicted effects are expected to naturally occur in artificial flat band lattices.

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Valley filtering in strain-induced α−T3 quantum dots

Cited by 18 publications

References 37 publications

Tunable valley filtering in dynamically strained $α$-$\mathcal{T}_3$ lattices

Tunable valley filtering in dynamically strained $α$-$\mathcal{T}_3$ lattices

Singular Flat Bands in the Modified Haldane-Dice Model

Size effects on atomic collapse in the dice lattice

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