Proposal for an All-Electrical Detection of Crossed Andreev Reflection in Topological Insulators

Reinthaler, R. W.; Recher, Patrik; Hankiewicz, Ewelina M.

doi:10.1103/physrevlett.110.226802

Cited by 50 publications

(49 citation statements)

References 43 publications

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“…The field of topological properties in condensed matter systems has been rapidly growing over the past decade. In particular, the topics of topological insulators (TIs) [1][2][3][4][5][6][7][8][9][10][11][12][13][14] and exotic bound states with non-Abelian statistics have attracted a lot of attention theoretically and experimentally . Of special interest are also quantum effects arising from geometric confinement such as topological insulator constrictions (TICs) [47][48][49][50][51][52], where the edge modes get coupled by tunneling and a gap is opened in the energy spectrum, see Fig.…”

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confidence: 99%

Fractional charge and spin states in topological insulator constrictions

Klinovaja

Loss

2015

Phys. Rev. B

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We investigate theoretically properties of two-dimensional topological insulator constrictions both in the integer and fractional regimes. In the presence of a perpedicular magnetic field, the constriction functions as a spin filter with near-perfect efficiency and can be switched by electric fields only. Domain walls between different topological phases can be created in the constriction as an interface between tunneling, magnetic fields, charge density wave, or electron-electron interactions dominated regions. These domain walls host non-Abelian bound states with fractional charge and spin and result in degenerate ground states with parafermions. If a proximity gap is induced bound states give rise to an exotic Josephson current with 8π-peridiodicity.

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confidence: 99%

Fractional charge and spin states in topological insulator constrictions

Klinovaja

Loss

2015

Phys. Rev. B

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“…7,[26][27][28][29][30] For example, in a two-dimensional (2D) topological insulator-superconductor-2D topological insulator junction, an all-electric Cooper-pair splitter was proposed by Reinthaler et al. 30 James et al 7 proposed an exclusive CAR device by inducing superconductivity on a AIII class topological insulator wire which supports two topological phases with one or two Majorana fermion end states. In the phase with two Majorana fermions, the LAR is completely suppressed at the normal lead/topological superconductor interface at zero bias, resulting in correlated and spin-polarized currents in the leads.…”

Section: Introductionmentioning

confidence: 99%

Crossed Andreev effects in two-dimensional quantum Hall systems

et al. 2016

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We study the crossed Andreev effects in two-dimensional conductor/superconductor hybrid systems under a perpendicular magnetic field. Both graphene/superconductor hybrid system and electron gas/superconductor one are considered. It is shown that an exclusive crossed Andreev reflection, with other Andreev reflections being completely suppressed, is obtained in a high magnetic field because of the chiral edge states in the quantum Hall regime. Importantly, the exclusive crossed Andreev reflection not only holds for a wide range of system parameters, e.g., the size of system, the width of central superconductor, and the quality of coupling between the graphene and the superconductor, but also is very robust against disorder. When the applied bias is within the superconductor gap, a perfect Cooper-pair splitting process with high-efficiency can be realized in this system.

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“…The only possible scattering channels are the electron transmission and reflection as a hole (Andreev reflection). When the excitation energy lies within the superconducting gap electron transmission must be zero and perfect Andreev reflection was predicted for both geometries, provided that the width of the ribbon is large enough to separate the counter propagating edge channels [27,28]. From matching the wave functions at the interface at x = 0 …”

Section: Transport Within the Btk Formalismmentioning

confidence: 99%

“…4a. If the system is large enough, the counter-propagating edge states with opposite spin do not hybridize and can be treated independently, while perfect Andreev reflection occurs at the NSC interface [27,28]. When a bias V is applied across the NSC junction we calculate the excess current I ex as well as the dI/dV characteristics within the BTK formalism [21,26] at finite temperature k B T = 0.1∆.…”

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confidence: 99%

Superconducting quantum spin Hall systems with giant orbitalgfactors

2015

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Topological aspects of superconductivity in quantum spin-Hall systems (QSHSs) such as thin layers of three-dimensional topological insulators (3D Tis) or two-dimensional Tis are in the focus of current research. We examine hybrid QSHS/superconductor structures in an external magnetic field and predict a gapless superconducting state with protected edge modes. It originates entirely from the orbital magnetic-field effect caused by the locking of the electron spin to the momentum of the superconducting condensate flow. We show that such spin-momentum locking can generate a giant orbital g-factor of order of several hundreds, allowing one to achieve significant spin polarization in the QSHS in the fields well below the critical field of the superconducting material. We propose a three-terminal setup in which the spin-polarized edge superconductivity can be probed by Andreev reflection, leading to unusual transport characteristics: a non-monotonic excess current and a zerobias conductance splitting in the absence of the Zeeman interaction.PACS numbers: 72.25. Dc, 73.23.Ad, 74.45.+c Introduction. Spin-Hall effects are one of the most active fields in modern solid state physics [1][2][3][4][5][6][7][8]. In particular, the quantum spin-Hall effect [5, 6, 9, 10] allows one to generate and convert charge and spin currents in protected edge channels [11]. Combining quantum spin-Hall systems (QSHSs) with superconductors (SCs) leads to a broader spectrum of interesting observable phenomena [12][13][14]. These include quantum interference effects reported in [13,14], indicating superconducting transport through the edge states in the QSH regime. Understanding edge superconductivity in QSHS/SC hybrids is also instrumental to the proposals to realize Majorana zero modes in topological insulators (see, e.g., [15] and reviews [16,17]).In this paper we predict a unique magnetic-field response of QSHS/SC hybrids which is characterized by very large effective g-factors reaching the order of several hundreds. It originates from the locking of the electron spin to the momentum of the superconducting condensate flow generated by an external magnetic field. We show that this orbital effect has the form similar to the Zeeman spin splitting in thin superconducting films [18], but involves an effective g-factor determined by the parameters of the QSHS/SC structure, viz.: the edge-state velocity, v, the thickness of the SC material, d SC , and the London penetration depth, λ L :

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Proposal for an All-Electrical Detection of Crossed Andreev Reflection in Topological Insulators

Cited by 50 publications

References 43 publications

Fractional charge and spin states in topological insulator constrictions

Fractional charge and spin states in topological insulator constrictions

Crossed Andreev effects in two-dimensional quantum Hall systems

Superconducting quantum spin Hall systems with giant orbitalgfactors

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