Weyl nodes in periodic structures of superconductors and spin-active materials

Motivated by recent progress in epitaxial growth of proximity structures of s-wave superconductors (S) and spin-active materials (M), in this paper we show that certain periodic structures of S and M can behave effectively as superconductors with pairs of point nodes, near which the low-energy excitations are Weyl fermions. A simple model, where M is described by a Kronig-Penney potential with both spin-orbit coupling and exchange field, is proposed and solved to obtain the phase diagram of the nodal structure, the spin texture of the Weyl fermions, as well as the zero-energy surface states in the form of open Fermi lines (Fermi arcs). As a second example, a lattice model with alternating layers of S and magnetic Z(2) topological insulators is solved. The calculated spectrum confirms previous predictions of Weyl nodes based on the tunnelling Hamiltonian of Dirac electrons. Our results provide further evidence that periodic structures of S and M are well suited for engineering gapless topological superconductors.


Singularities of spectra of infrared reflection of tertiary compounds of the type T1BX2
Hasanlı, Nızamı; Khomutova, M.D.; Sardarly, R.M.; Tagorov, V.I. (Springer Science and Business Media LLC, 1977-07-01)
The frequencies of lattice vibrations are calculated for compounds of the type T1BX2 on the basis of the linear-chain model. The calculated frequencies are compared with experimental values for TlGaS2 and TlGaSe2. The good agreement between the calculated and experimental frequencies serves as proof of the applicability of the linear-chain model to compounds of the T1BX2 type. The proposed method of calculation of frequencies makes it possible to predict the theoretical frequencies of lattice vibrations of ...
Singular potentials and moving boundaries in 3D
Yuce, C (Elsevier BV, 2004-02-16)
In this Letter, the problem of a spinless particle under the time-dependent harmonic oscillator potential and a singular potential with a moving boundary is studied in the spherical coordinates. Some transformations are used to transform the moving boundary conditions to the fixed boundary conditions. An exact solution is constructed.
Numerical investigation of flow and scour around a vertical circular cylinder
Baykal, Cüneyt; Fuhrman, D. R.; Jacobsen, N. G.; Fredsoe, J. (The Royal Society, 2015-01-28)
Flow and scour around a vertical cylinder exposed to current are investigated by using a three-dimensional numerical model based on incompressible Reynolds-averaged Navier-Stokes equations. The model incorporates (i) k-omega turbulence closure, (ii) vortex-shedding processes, (iii) sediment transport (both bed and suspended load), as well as (iv) bed morphology. The influence of vortex shedding and suspended load on the scour are specifically investigated. For the selected geometry and flow conditions, it i...
Hermitian and gauge-covariant Hamiltonians for a particle in a magnetic field on cylindrical and spherical surfaces
Shikakhwa, M. S.; Chair, N. (IOP Publishing, 2017-01-01)
We construct the Hermitian Schrodinger Hamiltonian of spin-less particles and the gauge-covariant Pauli Hamiltonian of spin one-half particles in a magnetic field, which are confined to cylindrical and spherical surfaces. The approach does not require the use of involved differential-geometrical methods and is intuitive and physical, relying on the general requirements of Hermicity and gauge-covariance. The surfaces are embedded in the full three-dimensional space and confinement to the surfaces is achieved...
Progressive structural and electronic properties of nano-structured carbon atomic chains
Usanmaz, D.; Srivastava, G. P. (AIP Publishing, 2013-05-21)
Ab initio calculations, based on the planewave pseudopotential method and the density functional theory, have been reported on the changes in the electronic and structural properties of short carbon atomic chains held rigidly between hydrogenated thin armchair graphene nanoribbons (N-a-AGNR) of dimer line numbers N-a = 4 and 5. We have considered chains of several lengths (n = 4-9 atoms) and with different forms of attachment with the AGNRs. It is found that odd-numbered chains are metallic in nature, with ...
Citation Formats
A. Keleş, “Weyl nodes in periodic structures of superconductors and spin-active materials,” PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY A-MATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES, pp. 0–0, 2018, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/34934.