Browsing by Author "Shapiro, I"

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Alternating para/diamagnetic domains in a p-wave superconductor
(2003-11-01)
Bel, G
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Rosenstein, B
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Shapiro, BY
;
Shapiro, I
;
電子物理學系
The mesoscopic one-dimensional magnetic texture caused by small Zeeman coupling in a p-wave superconductor in the magnetic field is found. The field orientation is opposite on the two sides of the texture and the magnitude can be even smaller than H-c1. The texture is not built from various singular topological defects, like vortices, as previously found in the simplest three-component Ginzburg-Landau model of superconductors.
Dynamics and thermal instability of magnetic flux in type-II superconductors
(2005-05-01)
Shapiro, BY
;
Shapiro, I
;
Rosenstein, B
;
Bass, F
;
電子物理學系
In recent experiments, trapped magnetic flux is initially generated by abrupt laser heating of a strip of a type-II superconducting film subjected to a weak magnetic field. We study herein the nonequilibrium penetration of the flux into the Meissner state area. Effects of the heal dissipation and transport on the motion and stability of the interface between the magnetic flux and flux-free domains are considered. It is shown that the magnetic induction and the temperature have the form of a shock wave moving with constant velocity as large as that corresponding to the depairing current. In the vicinity of the front, superconductivity is suppressed by strong screening currents. The front velocity is determined by the Joule heat caused by the electric current in the normal domain at the flux front. The stability of the shock wave solution is investigated both analytically and numerically. For sufficiently small heat diffusion constant a finger shaped thermal instability is found.
Hot spot in type-II superconductors: dynamics and instabilities
(2004-05-01)
Shapiro, B
;
Bel, G
;
Rosenstein, B
;
Shapiro, I
;
電子物理學系
The relaxation dynamics of a quenched normal spot in type-II superconductor is considered analytically and numerically. Various instabilities accompanying recovery of superconductivity are considered. Relaxation of the normal spot starts with appearance of a microscopic instability triggering the creation of the vortex clusters. (C) 2004 Elsevier B.V. All rights reserved.
Shock waves and avalanches in type-II superconductor
(2005-05-01)
Rosenstein, B
;
Shapiro, BY
;
Shapiro, I
;
電子物理學系
;
Department of Electrophysics
The rapid penetration of magnetic flux into a Meissner phase of the type-II superconductor is studied analytically and numerically. A sharp shock wave front of the magnetic induction is formed due to the singularity of the resistivity at the transition from the mixed to the normal state. It is shown that current densities at the front reach high values, of the order of the depairing current density. The effects of the heat dissipation and transport on the motion and stability of the interface between the magnetic flux and flux-free domains are considered. The shock wave magnetic induction and the temperature profiles move with constant velocity determined by the Joule heat produced by the electric current in the normal domain at the flux front. The stability of the shock wave solution is investigated. For a sufficiently small thermal-diffusion constant, a finger-shaped avalanche instability appears.
Unconventional vortices in multicomponent Ginzburg-Landau theory
(2002-06-01)
Pechenik, E
;
Rosenstein, B
;
Shapiro, BY
;
Shapiro, I
;
電子物理學系
Simulations of a three-component time-dependent Ginzburg-Landau (Abelian Higgs) model reveals that the dominant topological defects are vector vortices rather than conventional Abrikosov (Nielsen-Olesen) vortices or skyrmions. We describe in detail these vortices in the steady state and discuss their possible role in the dynamics. In particular, we conclude that the vector vortices have a superconducting core distinct from the superconducting bulk state. The profile of the vector order parameter and the magnetic field are calculated.
Upper critical magnetic field in superconducting Dirac semimetal
(2018-10-01)
Rosenstein, Baruch
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Shapiro, B. Ya
;
Li, Dingping
;
Shapiro, I
;
電子物理學系
Temperature dependence of the upper critical field H-c2 of the Dirac semimetal (DSM) with phonon-mediated pairing is considered within the semiclassical approximation. The low-temperature dependence deviates from conventional BCS superconductor with parabolic dispersion relation (WERTHAMER N. R., HELFAND E. and HOHENBERG P. C., Phys. Rev., 147 (1966) 295; HELFAND E. and WERTHAMER N. R., Phys. Rev. Lett., 13 (1964) 686) even for large adiabaticity parameter, gamma = mu/(sic)Omega), where mu is the chemical potential and Omega the Debye frequency. In particular the "reduced field", ratio of zero-temperature H (c2) to the derivative at critical temperature, h* = H (c2)(0)/(-T dH(c2)/dT)vertical bar T-c, depends on gamma and can be extended beyond the adiabatic limit. The reduced magnetic field ratio is universal (independent of the chemical potential, interaction strength, etc.) and smaller than the Werthamer ratio for clean superconductors: h* = 0.55 for DSM, h* (0) = 0.69 for parabolic band. The results are in good agreement compared with recent experiments on TaP. Copyright (C) EPLA, 2018