Intrinsic reduction of Josephson critical current in short ballistic SNS weak links

Nikolić, Branislav K.; Freericks, J. K.; Miller, Paul

doi:10.1103/physrevb.64.212507

Cited by 34 publications

(35 citation statements)

References 23 publications

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“…In order to obtain correct results for purely elastic scattering, metallic leads were attached at both ends of the system. In this case the formalism given above is equivalent [11] to the Landauer-Büttiker formulation [12]. To get the conductance g of the disordered region only, we have to subtract the contact resistance due to the leads.…”

Section: Model and Numerical Methods The Anderson Model Of Localisatiomentioning

confidence: 99%

Scaling at the energy‐driven metal‐insulator transition and the thermoelectric power

Römer

2006

Phys. Status Solidi (c)

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The electronic properties of disordered systems at the Anderson metal-insulator transition (MIT) have been the subject of intense study for several decades. Thermoelectric properties at the MIT, such as thermopower and thermal conductivity, however, have been relatively neglected. Using the recursive Green's function method and the Chester-Thellung-Kubo-Greenwood formalism, we calculate numerically the low temperature behaviour of all kinetic coefficients Lij. From these we can deduce for example the electrical conductivity σ and the thermopower S at finite temperatures. Here we present results for the case of completely coherent transport in cubic 3D systems.1 Introduction The Anderson model [1] is widely used to investigate the phenomenon of localisation in disordered materials. Especially the possibility of a quantum phase transition driven by disorder from an insulating phase, where all states are localised, to a metallic phase with extended states has lead to extensive analytical and numerical investigations of the critical properties of this metal-insulator transition (MIT) [2].The one-parameter scaling theory plays a crucial role in understanding the MIT [3]. It is based on an ansatz interpolating between metallic and insulating regimes [4]. So far, scaling has been demonstrated to an astonishing degree by numerical studies of the Anderson model [5]. However, most studies focused on scaling of the localisation length and the conductance at the disorder-driven MIT in the vicinity of the band centre.In the present paper, we will show numerical results for cubes of volume L 3 which are consistent with scaling also at the energy-driven transition across the mobility edge E c near the band tails. In particular, we find that at T = 0 the d.c. conductivity σ(E) close to E c is well described by the power-law [4,6]

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Section: Model and Numerical Methods The Anderson Model Of Localisatiomentioning

confidence: 99%

Scaling at the energy‐driven metal‐insulator transition and the thermoelectric power

Römer

2006

Phys. Status Solidi (c)

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“…Here Σ L(R) is the retarded self-energy associated with the left (right) lead. The self-energy contribution is computed by modeling each terminal as a semi-infinite perfect wire [47]. From Green's function , the local density of states (LDOS) can be found [46],…”

Section: Transport Properties Of Kmnrmentioning

confidence: 99%

Analytic and numeric computation of edge states and conductivity of a Kane-Mele nanoribbon

Sinha

Ganguly

Basu

2018

Physica E: Low-dimensional Systems and Nanostructures

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We compute analytic expressions for the edge states in a zigzag Kane-Mele nanoribbon (KMNR) by solving the eigenvalue equations in presence of intrinsic and Rashba spin-orbit couplings. Owing to the P-T symmetry of the Hamiltonian the edge states are protected by topological invariance and hence are found to be robust. We have done a systematic study for each of the above cases, for example, a pristine graphene, graphene with an intrinsic spin-orbit coupling, graphene with a Rashba spin-orbit coupling, a Kane-Mele nanoribbon and supported our results on the robustness of the edge states by analytic computation of the electronic probability amplitudes, the local density of states (LDOS), band structures and the conductance spectra.The successful fabrication of graphene [1] has generated intense research activities to study the electronic properties of this novel two dimensional (2D) electronic system. Graphene has a honeycomb lattice structure due to the sp 2 hybridization of carbon atoms and the π-electrons can hop between nearest neighbors. The valence and conduction bands of graphene touch each other at two nonequivalent Dirac points, K and K , which have opposite chiralities and form a time-reversed pair. The band structure around those points has the Dirac form, E k = v| k| , where v ( 10 6 ms −1 ) is the Fermi velocity. The Dirac nature of the electrons [2] is responsible for many interesting properties of graphene [3], such as unconventional quantum Hall effect [1,4,5], half metallicity [6,7], Klein tunneling through a barrier [8], high carrier mobility [9, 10] and many more. Owing to these features, graphene is recognized as one of the promising materials for realizing next-generation electronic devices.The existence of edge states in a graphene sheet is one of the interesting features in condensed matter physics. The properties of the edge states are different than the bulk states and play important roles in transport. When the valence and conduction bands are separated by an energy gap, electrons can not flow through the bulk. However, this does not guarantee that the system is a simple insulator, since conduction may still be allowed via edge modes. These new type of insulators are different from trivial insulators due to their unique gapless edge states protected by the time-reversal symmetry and they are attributed the name topological insulators. Thus topological insulators (TIs) represent a new quantum state. The phenomena associated with the TIs are the well known quantum Hall effect and the quantum spin Hall effect, where it has been found that the gapless chiral or helical edge states are robust channels with quantized conductance accompanied by non-vanishing values at zero bias [11,12,13,14,15,16,17,18]. Kane and Mele [13,14] predicted that a quantum spin Hall (QSH) state can be observed in presence of next-nearest neighbour intrinsic spin-orbit coupling (SOC), which triggered an enormous study on topologically non-trivial electronic materials [15,19,20,21]. Unfortunately, the QSH phase in prist...

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“…They are defined by the relation 42 , Here Σ L(R) is the retarded self-energy associated with the left (right) lead. The self-energy contribution is computed by modeling each terminal as a semi-infinite perfect wire 43 . Also the spin polarized conductance can be calculated from 44 ,…”

Section: Theoretical Formulation and Modelmentioning

confidence: 99%

Adatoms in graphene nanoribbons: spintronic properties and the quantum spin Hall phase

Ganguly¹,

Basu²

2017

Mater. Res. Express

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We study the charge and spin transport in a two terminal graphene nanoribbon (GNR) decorated with random Gold (Au) adatoms using a Kane-Mele model. Two commonly used GNRs, that is, the armchair graphene nanoribbon (AGNR) and the zigzag graphene nanoribbon (ZGNR) are compared and contrasted, which shows that in presence of Au adatoms, a somewhat robust 2e 2 /h conductance plateau occurs in the case of AGNR around the zero of the Fermi energy, while in ZGNR this plateau is fragile. We show that this flat plateau, having a conductance value 2e 2 /h, is not a hallmark signature of a topologically nontrivial quantum spin Hall (QSH) state. Further the conductance decreases by a small amount with the density of adatoms. On the other hand, the spin polarized conductance shows distinct features of enhanced conductivity with increasing Au adatom concentration. Further the fluctuations of the spin polarized conductance have features that carry striking resemblance with the charge conductance profile of the GNRs.

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Intrinsic reduction of Josephson critical current in short ballistic SNS weak links

Cited by 34 publications

References 23 publications

Scaling at the energy‐driven metal‐insulator transition and the thermoelectric power

Scaling at the energy‐driven metal‐insulator transition and the thermoelectric power

Analytic and numeric computation of edge states and conductivity of a Kane-Mele nanoribbon

Adatoms in graphene nanoribbons: spintronic properties and the quantum spin Hall phase

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