scholarly journals Disorder-induced suppression of the zero-bias conductance peak splitting in topological superconducting nanowires

2018 ◽  
Vol 9 ◽  
pp. 1358-1369 ◽  
Author(s):  
Jun-Tong Ren ◽  
Hai-Feng Lü ◽  
Sha-Sha Ke ◽  
Yong Guo ◽  
Huai-Wu Zhang
Keyword(s):  
Bound States ◽  
Chemical Potential ◽  
Zero Mode ◽  
Tight Binding ◽  
Fano Factor ◽  
Energy Splitting ◽  
Binding Model ◽  
Superconducting Nanowires ◽  
Zero Bias ◽  
Conductance Peak

We investigate the effect of three types of intrinsic disorder, including that in pairing energy, chemical potential, and hopping amplitude, on the transport properties through the superconducting nanowires with Majorana bound states (MBSs). The conductance and the noise Fano factor are calculated based on a tight-binding model by adopting a non-equilibrium Green’s function method. It is found that the disorder can effectively lead to a reduction in the conductance peak spacings and significantly suppress the peak height. Remarkably, for a longer nanowire, the zero-bias peak could be reproduced by weak disorder for a finite Majorana energy splitting. It is interesting that the shot noise provides a signature to discriminate whether the zero-bias peak is induced by Majorana zero mode or disorder. For Majorana zero mode, the noise Fano factor approaches zero in the low bias voltage limit due to the resonant Andreev tunneling. However, the Fano factor is finite in the case of a disorder-induced zero-bias peak.

scholarly journals Scalable Majorana vortex modes in iron-based superconductors

2020 ◽  
Vol 6 (9) ◽  
pp. eaay0443 ◽  
Author(s):  
Ching-Kai Chiu ◽  
T. Machida ◽  
Yingyi Huang ◽  
T. Hanaguri ◽  
Fu-Chun Zhang
Keyword(s):  
Tight Binding ◽  
Three Dimensional ◽  
Scanning Tunneling Spectroscopy ◽  
Scanning Tunneling ◽  
Zero Energy ◽  
Binding Model ◽  
Zero Bias ◽  
Iron Based Superconductors ◽  
Iron Based ◽  
Important Indication

The iron-based superconductor FeTexSe1−x is one of the material candidates hosting Majorana vortex modes residing in the vortex cores. It has been observed by recent scanning tunneling spectroscopy measurement that the fraction of vortex cores having zero-bias peaks decreases with increasing magnetic field on the surface of FeTexSe1−x. The hybridization of two Majorana vortex modes cannot simply explain this phenomenon. We construct a three-dimensional tight-binding model simulating the physics of over a hundred Majorana vortex modes in FeTexSe1−x. Our simulation shows that the Majorana hybridization and disordered vortex distribution can explain the decreasing fraction of the zero-bias peaks observed in the experiment; the statistics of the energy peaks off zero energy in our Majorana simulation are in agreement with the experiment. These agreements lead to an important indication of scalable Majorana vortex modes in FeTexSe1−x. Thus, FeTexSe1−x can be one promising platform having scalable Majorana qubits for quantum computing.

Phase Diagrams and Mixed States of Unconventional Superconductors

1998 ◽  
Vol 12 (29n31) ◽  
pp. 3031-3034
Author(s):  
Eugene A. Shapoval
Keyword(s):  
Phase Diagrams ◽  
Chemical Potential ◽  
Tight Binding ◽  
Square Lattice ◽  
Tight Binding Model ◽  
Mixed States ◽  
Binding Model ◽  
Unconventional Superconductors ◽  
Superconducting Phases

Using the BCS formalism we have calculated the phase diagrams of a tight-binding model on a square lattice as a function of temperature and chemical potential. The results include dx2-y2, dxy and (dx2-y2 ± idxy) superconducting phases.

scholarly journals A general algorithm for computing bound states in infinite tight-binding systems

2018 ◽  
Vol 4 (5) ◽  
Author(s):  
Mathieu Istas ◽  
Christoph Groth ◽  
Anton Akhmerov ◽  
Michael Wimmer ◽  
Xavier Waintal
Keyword(s):  
Bound States ◽  
Tight Binding ◽  
Quantum Spin ◽  
Edge States ◽  
Superconducting Nanowires ◽  
Topological Materials ◽  
Fermi Arcs ◽  
Scattering Matrices ◽  
Weyl Semimetals ◽  
Wave Matching

We propose a robust and efficient algorithm for computing bound states of infinite tight-binding systems that are made up of a finite scattering region connected to semi-infinite leads. Our method uses wave matching in close analogy to the approaches used to obtain propagating states and scattering matrices. We show that our algorithm is robust in presence of slowly decaying bound states where a diagonalization of a finite system would fail. It also allows to calculate the bound states that can be present in the middle of a continuous spectrum. We apply our technique to quantum billiards and the following topological materials: Majorana states in 1D superconducting nanowires, edge states in the 2D quantum spin Hall phase, and Fermi arcs in 3D Weyl semimetals.

The properties of Majorana bound states in topological superconductor nanowire

2020 ◽  
Vol 34 (15) ◽  
pp. 2050164
Author(s):  
Long Liu ◽  
Yu-Xian Li
Keyword(s):  
Magnetic Field ◽  
Bound States ◽  
Chemical Potential ◽  
Critical Value ◽  
Differential Conductance ◽  
Topological Phase ◽  
S Wave ◽  
Zero Bias ◽  
Topological Superconductor ◽  
The Magnetic Field

We investigate the differential conductance in topological superconductor nanowire. The appropriate proximity-induced s-wave superconductivity and an externally applied magnetic field can derive a critical value to illustrate the topological state of the nanowire. When the strength of magnetic field is below the critical value, the nanowire produces an interior gap, and the interior gap decreases as the magnetic field increases. When the magnetic field is bigger than the critical value, the interior gap disappears, and zero-bias conductance peak appears which indicates that nanowire transits into the topological phase. In particular, with increasing of the chemical potential, the nanowire is changed into the topological phase with more stronger magnetic field applied. As long as the spin-orbit coupling and magnetic field axes are perpendicular, the nanowire can always be transited into the topological phase at a sufficiently large magnetic field.

Superconducting Current-Phase Relation and Andreev Bound States in Nb/Au/YBa2Cu3Ox Josephson Heterojunctions

2003 ◽  
Vol 17 (10n12) ◽  
pp. 569-578 ◽  
Author(s):  
G. A. Ovsyannikov ◽  
P. V. Komissinski ◽  
Yu. V. Kislinski ◽  
Z. G. Ivanov
Keyword(s):  
Phase Relation ◽  
Bound States ◽  
Measurement Accuracy ◽  
Current Phase ◽  
Zero Bias ◽  
Shapiro Steps ◽  
Andreev Bound States ◽  
Conductance Peak ◽  
Zero Bias Conductance ◽  
Superconducting Current

Nb / Au / YBa 2 Cu 3 O x heterojunctions in (001) and (1 1 20)-oriented YBa 2 Cu 3 O x films have been fabricated. I-V curves of both kinds of heterojunctions show pronounced superconducting current. As affected by microwave radiation Shapiro steps at voltages hf/ 4e arise in the I-V curves of Nb / Au / YBa 2 Cu 3 O x (001) heterojunctions implying the double periodic (~ sin 2φ) superconducting current-phase relation. However, in the case of Nb / Au / YBa 2 Cu 3 O x (1 1 20) heterojunctions Shapiro steps have been observed in the I-V curves at voltages hf/ 2e only supporting a sinusoidal (~ sin φ) superconducting current-phase relation within measurement accuracy. A zero bias conductance peak associated with zero-energy Andreev bound states occurs in the I-V curve of the Nb / Au / YBa 2 Cu 3 O x (1 1 20) heterojunctions. We discuss the experimental results in terms of the d-wave symmetrical superconducting order parameter in YBCO.

Atomistic Study of Boron-Doped Silicon

1995 ◽  
Vol 408 ◽  
Author(s):  
M. Fearn ◽  
J. H. Jefferson ◽  
D. G. Pettifor
Keyword(s):  
Charge State ◽  
Density Functional ◽  
Chemical Potential ◽  
Tetrahedral Site ◽  
Tight Binding ◽  
Near Neighbor ◽  
Boron Diffusion ◽  
Binding Model ◽  
Teller Distortion ◽  
Silicon Vacancy

AbstractAtomistic simulations using both tight-binding and density-functional approaches have been performed to investigate boron-related defects in silicon. In agreement with experiment, the boron interstitial is shown to be a negative- U center in the sense that its neutral charge state, with an associated Jahn-Teller distortion off the ideal tetrahedral site, is never the ground state for any value of the chemical potential in the gap. The possible consequences for an electron-assisted migration of the interstitial are discussed. We also find the boron substitutional defect to be a next-nearest neighbor of a silicon vacancy in agreement with EPR spectra.A semi-empirical tight-binding model of the boron-silicon system is validated by direct comparison with the accurate density-functional results and is then used to perform molecular dynamics simulations of boron diffusion at high temperatures. The mobility of the interstitial is found to be strongly charge-state dependent. Termination of the boron interstitial migration path by recombination with a silicon vacancy is shown to be a very likely process with a number of configurations having no barrier to capture when the boron is a near-neighbor of the vacancy.

scholarly journals A Tight-Binding Grand Canonical Monte Carlo Study of the Catalytic Growth of Carbon Nanotubes

2008 ◽  
Vol 8 (11) ◽  
pp. 6099-6104 ◽  
Author(s):  
H. Amara ◽  
C. Bichara ◽  
F. Ducastelle
Keyword(s):  
Carbon Nanotubes ◽  
Monte Carlo ◽  
Chemical Potential ◽  
Tight Binding ◽  
Chemical Vapor ◽  
Catalyst Particle ◽  
Monte Carlo Study ◽  
Grand Canonical Monte Carlo ◽  
Binding Model ◽  
Grand Canonical

The nucleation of carbon nanotubes on small nickel clusters is studied using a tight binding model coupled to grand canonical Monte Carlo simulations. This technique follows the conditions of the synthesis of carbon nanotubes by chemical vapor deposition. The possible formation of a carbon cap on the catalyst particle is studied as a function of the carbon chemical potential, for particles of different size, either crystalline or disordered. We show that these parameters strongly influence the structure of the cap/particle interface which in turn will have a strong effect on the control of the structure of the nanotube. In particular, we discuss the presence of carbon on surface or in subsurface layers.

scholarly journals Cobalt-based magnetic Weyl semimetals with high-thermodynamic stabilities

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Wei Luo ◽  
Yuma Nakamura ◽  
Jinseon Park ◽  
Mina Yoon
Keyword(s):  
Tight Binding ◽  
Three Dimensional ◽  
Interlayer Coupling ◽  
First Principles Calculation ◽  
Optimization Approach ◽  
Binding Model ◽  
Nodal Lines ◽  
Weyl Semimetal ◽  
Topological Quantum ◽  
First Time

AbstractRecent experiments identified Co3Sn2S2 as the first magnetic Weyl semimetal (MWSM). Using first-principles calculation with a global optimization approach, we explore the structural stabilities and topological electronic properties of cobalt (Co)-based shandite and alloys, Co3MM’X2 (M/M’ = Ge, Sn, Pb, X = S, Se, Te), and identify stable structures with different Weyl phases. Using a tight-binding model, for the first time, we reveal that the physical origin of the nodal lines of a Co-based shandite structure is the interlayer coupling between Co atoms in different Kagome layers, while the number of Weyl points and their types are mainly governed by the interaction between Co and the metal atoms, Sn, Ge, and Pb. The Co3SnPbS2 alloy exhibits two distinguished topological phases, depending on the relative positions of the Sn and Pb atoms: a three-dimensional quantum anomalous Hall metal, and a MWSM phase with anomalous Hall conductivity (~1290 Ω−1 cm−1) that is larger than that of Co2Sn2S2. Our work reveals the physical mechanism of the origination of Weyl fermions in Co-based shandite structures and proposes topological quantum states with high thermal stability.

Sign in / Sign up

Export Citation Format

Share Document