HALF-CIRCULAR PILLAR IN A SUPERCONDUCTING SAMPLE

2013 ◽  
Vol 27 (12) ◽  
pp. 1350087 ◽  
Author(s):  
J. BARBA-ORTEGA ◽  
SINDY J. HIGUERA ◽  
J. ALBINO AGUIAR

In this paper, we solve the Ginzburg–Landau equations for a circular geometry containing a half-circular pillar. We consider the surface of the sample in a complete normal state (|ψ| surface = 0), this choice, leading to take the extrapolation de Gennes length equal to zero (b = 0). Our results point out that the critical fields, magnetization and vorticity, depend on the chosen boundary condition.

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Leonardo Rodrigues Cadorim ◽  
Alexssandre de Oliveira Junior ◽  
Edson Sardella

Abstract Within the framework of the generalized time-dependent Ginzburg–Landau equations, we studied the influence of the magnetic self-field induced by the currents inside a superconducting sample driven by an applied transport current. The numerical simulations of the resistive state of the system show that neither material inhomogeneity nor a normal contact smaller than the sample width are required to produce an inhomogeneous current distribution inside the sample, which leads to the emergence of a kinematic vortex–antivortex pair (vortex street) solution. Further, we discuss the behaviors of the kinematic vortex velocity, the annihilation rates of the supercurrent, and the superconducting order parameters alongside the vortex street solution. We prove that these two latter points explain the characteristics of the resistive state of the system. They are the fundamental basis to describe the peak of the current–resistance characteristic curve and the location where the vortex–antivortex pair is formed.


Open Physics ◽  
2004 ◽  
Vol 2 (1) ◽  
Author(s):  
G. Zharkov

AbstractThe self-consistent solutions of the nonlinear Ginzburg-Landau equations, which describe the behavior of a superconducting mesoscopic cylinder in an axial magnetic field H (provided there are no vortices inside the cylinder), are studied. Different, vortex-free states (M-, e-, d-, p-), which exist in a superconducting cylinder, are described. The critical fields (H 1, H 2, H p, H i, H r), at which the first or second order phase transitions between different states of the cylinder occur, are found as functions of the cylinder radius R and the GL-parameter $$\kappa $$ . The boundary $$\kappa _c (R)$$ , which divides the regions of the first and second order (s, n)-transitions in the icreasing field, is found. It is found that at R→∞ the critical value, is $$\kappa _c = 0.93$$ . The hysteresis phenomena, which appear when the cylinder passes from the normal to superconducting state in the decreasing field, are described. The connection between the self-consistent results and the linearized theory is discussed. It is shown that in the limiting case $$\kappa \to {1 \mathord{\left/ {\vphantom {1 {\sqrt 2 }}} \right. \kern-\nulldelimiterspace} {\sqrt 2 }}$$ and R ≫ λ (λ is the London penetration length) the self-consistent solution (which correponds to the socalled metastable p-state) coincides with the analitic solution found from the degenerate Bogomolnyi equations. The reason for the existence of two critical GL-parameters $$\kappa _0 = 0.707$$ and $$\kappa _0 = 0.93$$ in, bulk superconductors is discussed.


2014 ◽  
Vol 28 (31) ◽  
pp. 1450242
Author(s):  
Sindy J. Higuera ◽  
Miryam R. Joya ◽  
J. Barba-Ortega

In this work, we study the proximity and pinning effects of a rectangular superconducting anti-dot on the magnetization curve of a mesoscopic sample. We solve the nonlinear time-dependent Ginzburg–Landau equations for a superconducting rectangle in the presence of a magnetic field applied perpendicular to its surface. The pinning effects are determined by the number of vortices into the anti-dot. We calculate the order parameter, vorticity, magnetization and critical fields as a function of the external magnetic field. We found that the size and nature of the anti-dot strongly affect the magnetization of the sample. The results are discussed in framework of pinning and proximity effects in mesoscopic systems.


2020 ◽  
Vol 19 (1) ◽  
pp. 109-115 ◽  
Author(s):  
Cristian A Aguirre ◽  
MiryamR. Joya ◽  
J. Barba-Ortega

Solving the Ginzburg-Landau equations, we analyzed the vortex matter in a superconducting square with a Dimer structure of circular pinning centers generated by a pulsed heat source in presence of an applied magnetic field. We numerically solved the Ginzburg-Landau equations in order to describe the effect of the temperature of the circular defects on the Abrikosov state of the sample. The pulsed laser produced a variation of the temperature in each defect. It is shown that an anomalous vortex-anti-vortex state (A-aV) appears spontaneously at higher magnetic fields. This could be due to the breaking of the symmetry of the sample by the inclusion of the thermal defects


Respuestas ◽  
2020 ◽  
Vol 25 (1) ◽  
pp. 178-183
Author(s):  
Oscar Silva-Mosquera ◽  
Omar Yamid Vargas-Ramirez ◽  
José José Barba-Ortega

In the present work we analyze the effect of topological defects at different temperatures in a mesoscopic superconducting sample in the presence of an applied magnetic field H. The time-dependent Ginzburg-Landau equations are solved with the method of link variables. We study the magnetization curves M(H), number of vortices N(H) and Gibbs G(H) free energy of the sample as a applied magnetic field function. We found that the random distribution of the anchor centers for the temperatures used does not cause strong anchor centers for the vortices, so the configuration of fluxoids in the material is symmetrical due to the well-known Beam-Livingston energy barrier.


2014 ◽  
Vol 28 (18) ◽  
pp. 1450150
Author(s):  
J. Barba-Ortega ◽  
J. D. González ◽  
Miryam R. Joya

We study the Cooper pairs configuration, the magnetic induction and the magnetization in a superconducting nanoscopic square with a central square tower embedder in a uniform applied magnetic field. We study the vortex configurations for a superconductor in two scenarios; in the vicinity of the Bogomolny point [Formula: see text] and with [Formula: see text]. We also considered the Neumann and Dirichlet boundary conditions via deGennes length penetration. We show that the critical fields depends both on the boundary conditions and Ginzburg–Landau parameter.


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