Double Andreev reflections and double electron transmissions in a normal-superconductor-normal junction based on type-II Weyl semimetal

Li, Xue‐Si; Zhang, Shufeng; Sun, Xue-Rui; Gong, Wei‐Jiang

doi:10.1088/1367-2630/aae280

Cited by 16 publications

(15 citation statements)

References 41 publications

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“…[15][16][17][18][19][20] However, perfect ARs occur only for electrons incident from a certain direction, or a careful preparation of the interface is essential in these systems. [15][16][17][18][19][20] A topological Anderson insulator (TAI) is a special nontrivial phase induced by an Anderson insulator. [21][22][23][24] With no disorder, it is a normal metal with spin-orbital coupling.…”

Section: Introductionmentioning

confidence: 99%

“…[13,14] There is also theoretical studies in systems based on topological Weyl semimetals. [15][16][17][18][19][20] However, perfect ARs occur only for electrons incident from a certain direction, or a careful preparation of the interface is essential in these systems. [15][16][17][18][19][20] A topological Anderson insulator (TAI) is a special nontrivial phase induced by an Anderson insulator.…”

Section: Introductionmentioning

confidence: 99%

“…[ 13,14 ] There is also theoretical studies in systems based on topological Weyl semimetals. [ 15–20 ] However, perfect ARs occur only for electrons incident from a certain direction, or a careful preparation of the interface is essential in these systems. [ 15–20 ]…”

Section: Introductionmentioning

confidence: 99%

“…[ 15–20 ] However, perfect ARs occur only for electrons incident from a certain direction, or a careful preparation of the interface is essential in these systems. [ 15–20 ]…”

Section: Introductionmentioning

confidence: 99%

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A Perfect Andreev Reflection Induced by Anderson Disorder in a Normal–Superconductor Junction

Zhang

2021

Physica Status Solidi (b)

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The electronic transport properties of a 2D normal metal superconductor are studied by a nonequilibrium Green's function method. The normal metal is the non‐inverted HgTe/CdTe quantum well doped by electrons. It is found that Andreev reflection (AR) is enhanced in the weak disorder regime while weakened in the strong disorder regime. However, the AR coefficient can be perfect ( T normalA = 1 ) with vanished fluctuations in the moderate disorder regime, whereas other scattering processes are forbidden. The mechanism goes that Anderson disorder leads to a topological Anderson insulator with bulk states localized while edge states still extensive. Multiple ARs and spin‐momentum locking cooperate to vanish the normal reflection and leave AR only. A detailed numerical study shows that fixing the Fermi surface in conduction band, a large enough junction width, and a strong coupling between the normal and superconducting leads are necessary for perfect AR.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…[ 15–20 ] However, perfect ARs occur only for electrons incident from a certain direction, or a careful preparation of the interface is essential in these systems. [ 15–20 ]…”

Section: Introductionmentioning

confidence: 99%

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A Perfect Andreev Reflection Induced by Anderson Disorder in a Normal–Superconductor Junction

Zhang

2021

Physica Status Solidi (b)

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“…And it can open a new possibility to the much desired electric generation and detection of valley polarization [47]. Also, it can be used to get a new phase, the Weyl semimetal can be obtained by breaking the space-inversion symmetry of the Dirac semimetal [48,49]. In the past years, the effect of space-inversion symmetry breaking has been investigated in NS and NSN junctions, by considering its presence of the N part [50, 51].…”

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confidence: 99%

Andreev reflections modulated by the breaking of space-inversion symmetry in graphene-typed materials

Zhang

Gong

2019

New J. Phys.

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We theoretically perform a comprehensive analysis about the influences of the space-inversion symmetry breaking in graphene-based materials on the Andreev reflections (AR) in the normalmetal/superconductor (NS) and NSN heterojunctions. It is found that in the NS junction, the AR can be suppressed or be enhanced by the enhancement of space-inversion symmetry breaking, depending on the relationship among the coherence parameters. Following this result, the AR properties in the NSN structure are evaluated. It is readily observed that the local AR can be weakened for low spaceinversion symmetry breaking, and can be enhanced for high space-inversion symmetry breaking. Alternatively, the efficiency of the crossed AR can be improved to a great degree, with the increase of space-inversion symmetry breaking. One can therefore understand the special role of space-inversion symmetry in modulating the AR, especially for the enhancement of crossed AR. ferromagnetic leads are introduced to couple to the QDs, spin-polarized Andreev transport can be observed [34].On the other hand, graphene-based Cooper pair splitters have received a lot of attentions, after the successful fabrication of graphene. Graphene has the advantage of the controllability of its-based mesoscopic circuits, and it can be superconducting by proximity to a superconductor on top of it [35][36][37]. This has attracted vast studies in the electronic transport through the NS heterostructures based on graphene [38][39][40][41]. It is also known that graphene has the linear dispersion relation and the conduction and valence bands touch each other at the Dirac point, making it a gapless semiconductor. Hence in graphene, the carrier type (electron: n-type; hole: p-type) and its density can be easily tuned in a controllable manner by local electrostatic gates or chemical doping. Many groups have demonstrated that the two-dimensional crystals, e.g. graphene, are possible areas for CAR processes where the magnitude of the CAR conductance can be enhanced in NSN hybrid structures. By building the NSN structure with the n-type and p-type graphene coupled to the superconducting part, channels for the electron transmission (ET) and local Andreev reflection (LAR) processes have been found to be seriously suppressed, leading to the enhancement of CAR process [42]. Other researches try to improve the CAR efficiency by proposing a graphene-based NSN spin valve [43]. This shows a spin-switch effect between pure CAR process and pure ET through the reverse of the magnetization direction in the ferromagnetic layers. Besides, a pure CAR process has been observed in a magnetized zigzag graphene nanoribbon junction with an even zigzag chain number [44].It is well known that besides the physical real spin index in graphene, one additional intrinsic degree of freedom also affects the properties of graphene, due to the existence of two types of carbon atoms (labeled as A and B) in the honeycomb lattice of graphene. When A and B atoms are different in energy, the space-inversion symmetry ...

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Double Andreev reflections at surface states of the topological insulators with hexagonal warping

et al. 2019

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Double Andreev reflections and double electron transmissions in a normal-superconductor-normal junction based on type-II Weyl semimetal

Cited by 16 publications

References 41 publications

A Perfect Andreev Reflection Induced by Anderson Disorder in a Normal–Superconductor Junction

A Perfect Andreev Reflection Induced by Anderson Disorder in a Normal–Superconductor Junction

Andreev reflections modulated by the breaking of space-inversion symmetry in graphene-typed materials

Double Andreev reflections at surface states of the topological insulators with hexagonal warping

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