scholarly journals Effects of tilting the magnetic field in one-dimensional Majorana nanowires

2014 ◽  
Vol 89 (24) ◽  
Author(s):  
Javier Osca ◽  
Daniel Ruiz ◽  
Llorenç Serra
Keyword(s):  
Magnetic Field ◽  
One Dimensional ◽  
The Magnetic Field

scholarly journals The influence of resistivity gradients on shock conditions for a Petschek reconnection geometry

2016 ◽  
Vol 34 (4) ◽  
pp. 421-425
Author(s):  
Christian Nabert ◽  
Karl-Heinz Glassmeier
Keyword(s):  
Magnetic Field ◽  
Necessary Conditions ◽  
The Other ◽  
Diffusion Region ◽  
Two Dimensional ◽  
Characteristic Velocity ◽  
Magnetohydrodynamic Equations ◽  
One Dimensional ◽  
The Magnetic Field ◽  
Alfven Velocity

Abstract. Shock waves can strongly influence magnetic reconnection as seen by the slow shocks attached to the diffusion region in Petschek reconnection. We derive necessary conditions for such shocks in a nonuniform resistive magnetohydrodynamic plasma and discuss them with respect to the slow shocks in Petschek reconnection. Expressions for the spatial variation of the velocity and the magnetic field are derived by rearranging terms of the resistive magnetohydrodynamic equations without solving them. These expressions contain removable singularities if the flow velocity of the plasma equals a certain characteristic velocity depending on the other flow quantities. Such a singularity can be related to the strong spatial variations across a shock. In contrast to the analysis of Rankine–Hugoniot relations, the investigation of these singularities allows us to take the finite resistivity into account. Starting from considering perpendicular shocks in a simplified one-dimensional geometry to introduce the approach, shock conditions for a more general two-dimensional situation are derived. Then the latter relations are limited to an incompressible plasma to consider the subcritical slow shocks of Petschek reconnection. A gradient of the resistivity significantly modifies the characteristic velocity of wave propagation. The corresponding relations show that a gradient of the resistivity can lower the characteristic Alfvén velocity to an effective Alfvén velocity. This can strongly impact the conditions for shocks in a Petschek reconnection geometry.

Effects of Magnetic Fields on PN Junctions in Piezomagnetic–Piezoelectric Semiconductor Composite Fibers

2020 ◽  
Vol 12 (08) ◽  
pp. 2050085
Author(s):  
Chao Liang ◽  
Chunli Zhang ◽  
Weiqiu Chen ◽  
Jiashi Yang
Keyword(s):  
Magnetic Field ◽  
Composite Fiber ◽  
Transverse Magnetic ◽  
Piezoelectric Semiconductor ◽  
One Dimensional ◽  
Current Voltage ◽  
Potential Applications ◽  
Multiferroic Composite ◽  
The Magnetic Field ◽  
Current Voltage Relation

We study the electromechanical and electrical behaviors of a PN junction in a multiferroic composite fiber, consisting of a piezoelectric semiconductor (PS) layer between two piezomagnetic (PM) layers, under a transverse magnetic field. Based on the derived one-dimensional model for multiferroic composite semiconductor structures, we obtain the linear analytical solution for the built-in potential and electric field in the junction when there is no applied voltage between the two ends of the fiber. When a bias voltage is applied over the two ends of the fiber, a nonlinear numerical analysis is performed for the current–voltage relation. Both a homogeneous junction with a uniform PS layer and a heterogeneous junction with two different PSs on different sides of the junctions are studied. It is found that overall the homogeneous junction is essentially unaffected by the magnetic field, and the heterojunction is sensitive to the magnetic field with potential applications in piezotronics.

Travelling fronts in nonlocal models for phase separation in an external field

1997 ◽  
Vol 127 (4) ◽  
pp. 823-835 ◽  
Author(s):  
Enza Orlandi ◽  
Livio Triolo
Keyword(s):  
Magnetic Field ◽  
Metastable Phase ◽  
Glauber Dynamics ◽  
One Dimensional ◽  
Kac Potentials ◽  
Nonlocal Models ◽  
Nonlocal Evolution Equation ◽  
Travelling Fronts ◽  
The One ◽  
The Magnetic Field

We consider the one-dimensional, nonlocal, evolution equation derived by De Masi et al. (1995) for Ising systems with Glauber dynamics, Kac potentials and magnetic field. We prove the existence of travelling fronts, their uniqueness modulo translations among the monotone profiles and their linear stability for all the admissible values of the magnetic field for which the underlying spin system exhibits a stable and metastable phase.

scholarly journals Magnetic relaxation and the Taylor conjecture

2015 ◽  
Vol 81 (6) ◽  
Author(s):  
H. K. Moffatt
Keyword(s):  
Magnetic Field ◽  
Initial Phase ◽  
Magnetic Relaxation ◽  
Magnetic Energy ◽  
Magnetic Pressure ◽  
Second Phase ◽  
One Dimensional ◽  
Induction Equation ◽  
Two Phases ◽  
The Magnetic Field

A one-dimensional model of magnetic relaxation in a pressureless low-resistivity plasma is considered. The initial two-component magnetic field $\boldsymbol{b}(\boldsymbol{x},t)$ is strongly helical, with non-uniform helicity density. The magnetic pressure gradient drives a velocity field that is dissipated by viscosity. Relaxation occurs in two phases. The first is a rapid initial phase in which the magnetic energy drops sharply and the magnetic pressure becomes approximately uniform; the helicity density is redistributed during this phase but remains non-uniform, and although the total helicity remains relatively constant, a Taylor state is not established. The second phase is one of slow diffusion, in which the velocity is weak, though still driven by persistent weak non-uniformity of magnetic pressure; during this phase, magnetic energy and helicity decay slowly and at constant ratio through the combined effects of pressure equalisation and finite resistivity. The density field, initially uniform, develops rapidly (in association with the magnetic field) during the initial phase, and continues to evolve, developing sharp maxima, throughout the diffusive stage. Finally it is proved that, if the resistivity is zero, the spatial mean $\langle (\boldsymbol{b}\boldsymbol{\cdot }\boldsymbol{{\rm\nabla}}\times \boldsymbol{b})/b^{2}\rangle$ is an invariant of the governing one-dimensional induction equation.

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