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.

scholarly journals Topological isoconductance signatures in Majorana nanowires

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
L. S. Ricco ◽  
J. E. Sanches ◽  
Y. Marques ◽  
M. de Souza ◽  
M. S. Figueira ◽  
...  
Keyword(s):  
Quantum Dot ◽  
Transport Properties ◽  
Spin Polarization ◽  
Bound States ◽  
Spin Asymmetry ◽  
Experimental Protocol ◽  
Zero Bias ◽  
Topological Superconductor ◽  
Hybrid Device ◽  
Majorana Bound States

AbstractWe consider transport properties of a hybrid device composed by a quantum dot placed between normal and superconducting reservoirs, and coupled to a Majorana nanowire: a topological superconducting segment hosting Majorana bound states (MBSs) at the opposite ends. It is demonstrated that if highly nonlocal and nonoverlapping MBSs are formed in the system, the zero-bias Andreev conductance through the dot exhibits characteristic isoconductance profiles with the shape depending on the spin asymmetry of the coupling between the dot and the topological superconductor. Otherwise, for overlapping MBSs with less degree of nonlocality, the conductance is insensitive to the spin polarization and the isoconductance signatures disappear. This allows to propose an alternative experimental protocol for probing the nonlocality of the MBSs in Majorana nanowires.

scholarly journals Equation of State of a Magnetized Dense Neutron System

Universe ◽  
2019 ◽  
Vol 5 (5) ◽  
pp. 104 ◽  
Author(s):  
Efrain J. Ferrer ◽  
Aric Hackebill
Keyword(s):  
Magnetic Field ◽  
Equation Of State ◽  
Chemical Potential ◽  
Compact Objects ◽  
Field Direction ◽  
Neutron Density ◽  
Magnetic Field Direction ◽  
System Equation ◽  
The One ◽  
The Magnetic Field

We discuss how a magnetic field can affect the equation of state of a many-particle neutron system. We show that, due to the anisotropy in the pressures, the pressure transverse to the magnetic field direction increases with the magnetic field, while the one along the field direction decreases. We also show that in this medium there exists a significant negative field-dependent contribution associated with the vacuum pressure. This negative pressure demands a neutron density sufficiently high (corresponding to a baryonic chemical potential of μ = 2.25 GeV) to produce the necessary positive matter pressure that can compensate for the gravitational pull. The decrease of the parallel pressure with the field limits the maximum magnetic field to a value of the order of 10 18 G, where the pressure decays to zero. We show that the combination of all these effects produces an insignificant variation of the system equation of state. We also found that this neutron system exhibits paramagnetic behavior expressed by the Curie’s law in the high-temperature regime. The reported results may be of interest for the astrophysics of compact objects such as magnetars, which are endowed with substantial magnetic fields.

scholarly journals ANOMALOUS DEFECTS AND THEIR QUANTIZED TRANSVERSE CONDUCTIVITIES

1998 ◽  
Vol 13 (05) ◽  
pp. 841-861 ◽  
Author(s):  
A. P. BALACHANDRAN ◽  
VARGHESE JOHN ◽  
ARSHAD MOMEN ◽  
FERNANDO MORAES
Keyword(s):  
Magnetic Field ◽  
Field Theory ◽  
Bound States ◽  
Three Dimensional ◽  
External Electromagnetic Field ◽  
Effective Field ◽  
Screw Dislocations ◽  
Dimensional Gravity ◽  
The Magnetic Field ◽  
Conduction Properties

Using a description of defects in solids in terms of three-dimensional gravity, we study the propagation of electrons in the background of disclinations and screw dislocations. We study the situations where there are bound states that are effectively localized on the defect and hence can be described in terms of an effective (1+1)-dimensional field theory for the low energy excitations. In the case of screw dislocations, we find that these excitations are chiral and can be described by an effective field theory of chiral fermions. Fermions of both chirality occur even for a given direction of the magnetic field. The "net" chirality of the system however is not always the same for a given direction of the magnetic field, but changes from one sign of the chirality through zero to the other sign as the Fermi momentum or the magnitude of the magnetic flux is varied. On coupling to an external electromagnetic field, the latter becomes anomalous and predicts novels conduction properties for these material.

THE EFFECT OF POSITION DEPENDENT EFFECTIVE MASS OF HYDROGENIC IMPURITIES IN PARABOLIC GaAs/GaAlAs QUANTUM DOTS IN A STRONG MAGNETIC FIELD

2009 ◽  
Vol 23 (26) ◽  
pp. 5109-5118 ◽  
Author(s):  
A. JOHN PETER
Keyword(s):  
Magnetic Field ◽  
Quantum Dots ◽  
Binding Energy ◽  
Effective Mass ◽  
Bound States ◽  
Mass Approximation ◽  
Infinite Case ◽  
Dependent Mass ◽  
The Magnetic Field ◽  
Peak Value

The binding energy of shallow hydrogenic impurities in parabolic GaAs/GaAlAs quantum dots is calculated as a function of dot radius in the influence of magnetic field. The binding energy has been calculated following a variational procedure within the effective-mass approximation. Calculations are presented with constant effective-mass and position dependent effective masses. A finite confining potential well with depth is determined by the discontinuity of the band gap in the quantum dot and the cladding. The results show that the impurity binding energy (i) increases as the dot radius decreases for the infinite case, (ii) reaches a peak value around 1R* as the dot radius decreases and then diminishes to a limiting value corresponding to the radius for which there are no bound states in the well for the infinite case, and (iii) increases with the magnetic field. Also it is found that (i) the use of constant effective mass (0.067 m0) is justified for dot sizes ≥ a* where a* is the effective Bohr radius which is about 100 Å for GaAs , in the estimation of ionization energy and (ii) the binding energy shows complicated behavior when the position dependent mass is included for the dot size ≤ a*. These results are compared with the available existing literatures.

Article

1998 ◽  
Vol 76 (7) ◽  
pp. 507-513
Author(s):  
O Bolina ◽  
J R Parreira
Keyword(s):  
Magnetic Field ◽  
Transverse Magnetic Field ◽  
Ground State ◽  
Linear Chain ◽  
Critical Value ◽  
Transverse Magnetic ◽  
The State ◽  
Xy Model ◽  
The Magnetic Field

We show that the ground state of the xy model (ferromagnetic orantiferromagnetic) in a transverse magnetic field h --- for any spin value, in any dimension --- is the state with all spins aligned antiparallel to the field when h is greater than some critical value hc. In particular, for the spin-1/2 linear chain, we study the behavior of correlations as functions of the magnetic field. PACS Nos.: 75.10Jm and 64.60.Cm

scholarly journals Особенности поведения ионов Mn-=SUP=-2+-=/SUP=- в 3D-дираковском полуметалле alpha-Cd-=SUB=-3-=/SUB=-As-=SUB=-2-=/SUB=- по данным ЭПР

2021 ◽  
Vol 63 (2) ◽  
pp. 199
Author(s):  
Ю.В. Горюнов ◽  
А.Н. Натепров
Keyword(s):  
Magnetic Field ◽  
Free Electron ◽  
Bound States ◽  
High Manganese ◽  
Contact Potential ◽  
Conduction Electrons ◽  
Europium Doping ◽  
Dirac Semimetal ◽  
Electromagnetic Measurements ◽  
The Magnetic Field

The behavior of the manganese impurity in the 3D Dirac semimetal Cd3As2 has been studied by EPR and electromagnetic measurements. It was found that, in contrast to doping with europium, doping with manganese, as well as with iron, does not lead to a change in the sign of the magnetoresistance, which is almost completely suppressed at high manganese concentrations. In this case, a change in the type of the influence of the magnetic field on the contact potential is manifested. The g-factors measured in EPR coincide with the g-factor of a free electron at all temperatures, which, taking into account the fluctuation behavior of the EPR linewidth and the reduced magnetic moment on Mn2 +, indicates the formation of short-lived bound states of the Mn2 + ion and conduction electrons - antiferromagnetic polarons.

scholarly journals Критический ток в длинном джозефсоновском контакте во внешнем магнитном поле при слабом пиннинге

2022 ◽  
Vol 92 (3) ◽  
pp. 414
Author(s):  
М.А. Зеликман
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Critical Current ◽  
Critical Value ◽  
Transport Current ◽  
Entire Length ◽  
Gibbs Potential ◽  
Potential Reduction ◽  
The Magnetic Field ◽  
Josephson Contact

The analysis of possible current distributions when passing current through a periodically modulated long Josephson contact located in an external magnetic field is carried out. An approach based on the analysis of continuous configuration modification proceeding in the direction of Gibbs potential reduction is used for the calculation. The case when the pinning parameter is less than the critical value is considered. It is shown that at any value of the external magnetic field, there is a critical value of the transport current, when exceeded, the situation ceases to be stationary, as a result of which energy passes into radiation and heat, i.e. currents cease to be persistent. The value of the critical current is determined by the value of the magnetic field at which the vortices begin to fill the entire length of the contact. With an increase in the external magnetic field, the critical value of the current decreases.

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 Evolution of quasi-bound states in the circular n–p junction of bilayer graphene under magnetic field

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Haijiao Ji ◽  
Yueting Pan ◽  
Haiwen Liu
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Bound States ◽  
Local Density ◽  
Energy Levels ◽  
Bilayer Graphene ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Weak Magnetic Fields ◽  
The Magnetic Field

Abstract Electron in gapless bilayer graphene can form quasi-bound states when a circular symmetric potential is created in bilayer graphene. These quasi-bound states can be adjusted by tuning the radius and strength of the potential barrier. We investigate the evolution of quasi-bound states spectra in the circular n–p junction of bilayer graphene under the magnetic field numerically. The energy levels of opposite angular momentum split and the splitting increases with the magnetic field. Moreover, weak magnetic fields can slightly shift the energy levels of quasi-bound states. While strong magnetic fields induce additional resonances in the local density states, which originates from Landau levels. We demonstrate that these numerical results are consistent with the semiclassical analysis based on Wentzel–Kramers–Brillouin approximation. Our results can be verified experimentally via scanning tunneling microscopy measurements.

scholarly journals Critical end point in a thermomagnetic nonlocal NJL model

2017 ◽  
Vol 32 (26) ◽  
pp. 1750162 ◽  
Author(s):  
F. Márquez ◽  
R. Zamora
Keyword(s):  
Magnetic Field ◽  
Phase Transition ◽  
Phase Diagram ◽  
Order Phase Transition ◽  
Chemical Potential ◽  
First Order ◽  
End Point ◽  
First Order Phase Transition ◽  
First Order Phase ◽  
The Magnetic Field

In this paper, we explore the critical end point in the [Formula: see text] phase diagram of a thermomagnetic nonlocal Nambu–Jona-Lasinio model in the weak field limit. We work with the Gaussian regulator, and find that a crossover takes place at [Formula: see text], [Formula: see text]. The crossover turns to a first-order phase transition as the chemical potential or the magnetic field increases. The critical end point of the phase diagram occurs at a higher temperature and lower chemical potential as the magnetic field increases. This result is in accordance to similar findings in other effective models. We also find that there is a critical magnetic field, for which a first-order phase transition takes place even at [Formula: see text].

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