Electronic properties of α − 𝒯3 quantum dots in magnetic fields

Filusch, Alexander; Fehske, Holger

doi:10.1140/epjb/e2020-10178-2

Cited by 5 publications

(3 citation statements)

References 74 publications

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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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Section: Introductionmentioning

confidence: 99%

Size effects on atomic collapse in the dice lattice

Oriekhov,

Voronov

2023

J. Phys.: Condens. Matter

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“…There are also several suggestions for an optical α-T 3 lattice that would allow a tuning of α by dephasing one pair of the three counter-propagating laser beams [28,30]. Under external electromagnetic fields, the flat band and α-dependent Berry phase have striking consequences on the Landau level quantization [28,31], the quantum Hall effect [32,33], Klein tunneling [34][35][36][37] and Weiss oscillations [38]. While the flat band has zero group ve-locity and therefore zero conductivity, it is predicted to play an important role for the transport by its nontrivial topology [29,44], the coupling to propagating bands [39][40][41], or interaction effects [42][43][44][45].…”

Section: Introductionmentioning

confidence: 99%

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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“…The combination of strain, Dirac-cone physics, and flat-band physics in a modified α-T 3 lattice structure is an interesting case to study, not only because the flat band then crosses the nodal Dirac points with peculiar consequences for the Berry phase [18], Klein tunneling [19], Weiss oscillations [20], or LL quantization [21], but also regarding the interplay between the local inversion symmetry breaking by strain and the global one by α. In the α-T 3 structure one of the inequivalent sites of the honeycomb lattice is connected to a site located in the center of the hexagons with strength α, i.e., in a certain sense this system interpolates between graphene (α = 0) and dice (α = 1) lattices [22].…”

Section: Introductionmentioning

confidence: 99%

Valley filtering in strain-induced $α$-$\mathcal{T}_3$ quantum dots

Filusch,

Bishop,

Saxena

et al. 2021

Preprint

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We test the valley-filtering capabilities of a quantum dot inscribed by locally straining an α-T3 lattice. Specifically, we consider an out-of-plane Gaussian bump in the center of a four-terminal configuration and calculate the generated pseudomagnetic field having an opposite direction for electrons originating from different valleys, the resulting valley-polarized currents, and the conductance between the injector and collector situated opposite one another. Depending on the quantum dot's width and width-to-height ratio, we detect different transport regimes with and without valley filtering for both the α-T3 and dice lattice structures. In addition, we analyze the essence of the conductance resonances with a high valley polarization in terms of related (pseudo-) Landau levels, the spatial distribution of the local density of states, and the local current densities. The observed local charge and current density patterns reflect the local inversion symmetry breaking by the strain, besides the global inversion symmetry breaking due to the scaling parameter α. By this way we can also filter out different sublattices.

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Electronic properties of α − 𝒯3 quantum dots in magnetic fields

Cited by 5 publications

References 74 publications

Size effects on atomic collapse in the dice lattice

Size effects on atomic collapse in the dice lattice

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

Valley filtering in strain-induced $α$-$\mathcal{T}_3$ quantum dots

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