Topology from triviality

Kaladzhyan, Vardan; Bena, Cristina; Simon, Pascal

doi:10.1103/physrevb.97.104512

Cited by 10 publications

(19 citation statements)

References 39 publications

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“…[38] The transport properties of Weyl semimetal nanowires have been already studied by using the scattering matrix approach and numerical methods in refs. [39][40][41]. Remarkably, it was shown that the contribution of the Fermi arc states to the electric current induced by a slowly varying magnetic field can be significant and even comparable to that of the bulk states regardless of the system size.…”

Section: Introductionmentioning

confidence: 99%

“…Recently, it was explicitly demonstrated [41] that the existence of the surface and bulk states allows for two transport regimes. In the surface regime, the current is carried by the Fermi arc surface states with conductance increasing in steps as a function of the electric chemical potential when it lies in the bulk confinement gap due to the finite size of a sample.…”

Section: Introductionmentioning

confidence: 99%

“…The interplay of magnetic field and surface states in the magnetotransport of Weyl semimetals was also investigated in refs. [41,46,47]. Among other interesting effects, the presence of the Fermi arcs allows for the closed surface-bulk orbits when a magnetic field is perpendicular to a slab of Weyl semimetal.…”

Section: Introductionmentioning

confidence: 99%

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Fermi Arcs and DC Transport in Nanowires of Dirac and Weyl Semimetals

et al. 2020

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The transport properties and electron states in cylinder nanowires of Dirac and Weyl semimetals are studied paying special attention to the structure and properties of the surface Fermi arcs. The latter make the electric charge and current density distributions in nanowires strongly nonuniform as the majority of the charge density is accumulated at the surface. It is found that a Weyl semimetal wire also supports a magnetization current localized mainly at the surface because of the Fermi arcs contribution. By using the Kubo linear response approach, the direct current (DC) conductivity is calculated and it is found that its spatial profile is nontrivial. By explicitly separating the contributions of the surface and bulk states, it is shown that when the electric chemical potential and/or the radius of the wire is small, the electron transport is determined primarily by the Fermi arcs and the electrical conductivity is much higher at the surface than in the bulk. Due to the rise of the surface‐bulk transition rate, the relative contribution of the surface states to the total conductivity gradually diminishes as the chemical potential increases. In addition, the DC conductivity at the surface demonstrates noticeable peaks when the Fermi level crosses energies of the surface states.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Fermi Arcs and DC Transport in Nanowires of Dirac and Weyl Semimetals

et al. 2020

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“…If these adatoms order magnetically the chain can become a 1D topological superconductor, even if the underlying superconductor is of s-wave spin-singlet type. [12][13][14][15][16][17][18][19][20][21][22][23][24][25][26] The key point in this construction is that magnetic impurities in s-wave superconductors feature socalled Shiba midgap bound states, 18,21,[27][28][29][30] which can hybridize along the chain and experience band inversion. The appearance of Shiba states can be intuitively understood from "Anderson's theorem", 31 stating that s-wave superconductivity is (locally) suppressed by magnetic impurities.…”

Section: -11mentioning

confidence: 99%

Shiba chains of scalar impurities on unconventional superconductors

2016

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We show that a chain of nonmagnetic impurities deposited on a fully gapped two-or threedimensional superconductor can become a topological one-dimensional superconductor with protected Majorana bound states at its end. A prerequisite is that the pairing potential of the underlying superconductor breaks the spin-rotation symmetry, as it is generically the case in systems with strong spin-orbit coupling. We illustrate this mechanism for a spinless triplet-superconductor (px + ipy) and a time-reversal symmetric Rashba superconductor with a mixture of singlet and triplet pairing. For the latter, we show that the impurity chain can be topologically nontrivial even if the underlying superconductor is topologically trivial.

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“…The total Hamiltonian consists of the sum H = H (bulk) + H (imp) . Each potential impurity atom binds a single physical subgap state [42][43][44], which in the BdG formalism is represented by a pair of states at energies ε = ± where v F is the Fermi velocity and ν the density of states in the bulk [45].…”

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confidence: 99%

Topological state engineering by potential impurities on chiral superconductors

et al. 2016

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In this work we consider the influence of potential impurities deposited on top of two-dimensional chiral superconductors. As discovered recently, magnetic impurity lattices on an s-wave superconductor may give rise to a rich topological phase diagram. We show that a similar mechanism takes place in chiral superconductors decorated by nonmagnetic impurities, thus avoiding the delicate issue of magnetic ordering of adatoms. We illustrate the method by presenting the theory of potential impurity lattices embedded on chiral p-wave superconductors. While a prerequisite for the topological state engineering is a chiral superconductor, the proposed procedure results in vistas of nontrivial descendant phases with different Chern numbers. DOI: 10.1103/PhysRevB.94.060505 Introduction. Engineering novel quantum phases of matter with exotic properties is a rapidly growing trend in contemporary physics. The main goal is to employ simpler and wellunderstood ingredients and methods to create more complex structures with desirable properties. Recent promising efforts to realize [1][2][3] topological superconductivity in nanowire systems [4,5] demonstrate the power of the approach. While it seems unlikely that Nature directly provides us with Majorana quasiparticles that could be employed in quantum information applications [6], it is increasingly probable that those can be achieved in the laboratory. In the spirit of engineering novel controllable states of matter, we show how to realize a complex hierarchy of topological phases with potential impurity superstructures adsorbed on chiral superconductors. Magnetic atoms on s-wave superconductors give rise to Yu-Shiba-Rusinov subgap states [7][8][9][10] which have been probed experimentally by scanning tunneling microscopy (STM) [11][12][13][14]. Superstructures fabricated from magnetic atoms are currently under active experimental [15][16][17] and theoretical research [18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33]. Intriguing properties of these systems include the possibility for various one-dimensional (1D) topological superconducting phases with Majorana bound states and rich two-dimensional (2D) topological phases [34][35][36][37]. A topologically nontrivial phase is known to arise in 1D ferromagnetic arrays when the underlying superconductor has a strong Rasha spin-orbit coupling or in arrays with helical magnetic textures. In 1D structures there are theoretical arguments why magnetic self-tuning could result in a nontrivial ground state [20][21][22]28,32,38], though in real systems there are a number of complications. In particular, in 2D structures the nature and tunability of magnetic textures is a delicate and largely unsolved question.Very recently it was proposed that potential impurities could be utilized to realize interesting topological states in 1D structures [39] and 2D toy models [40]. The procedure requires a non-s-wave superconductor host material with chiral or helical pairing components but circumvents the need for specific magnetic tex...

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Topology from triviality

Cited by 10 publications

References 39 publications

Fermi Arcs and DC Transport in Nanowires of Dirac and Weyl Semimetals

Fermi Arcs and DC Transport in Nanowires of Dirac and Weyl Semimetals

Shiba chains of scalar impurities on unconventional superconductors

Topological state engineering by potential impurities on chiral superconductors

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