scholarly journals Simple theoretical proposal of the dependence of the deGennes extrapolation parameter with the surface temperature of a superconducting sample

TecnoLógicas ◽  
2019 ◽  
Vol 22 (45) ◽  
pp. 1-7 ◽  
Author(s):  
José José Barba-Ortega ◽  
Jesús D. González ◽  
Miryam Rincón-Joya
Keyword(s):  
Vortex State ◽  
B Value ◽  
Continuous Laser ◽  
Single Vortex ◽  
Ginzburg Landau ◽  
Laser Wave ◽  
Superconducting Sample ◽  
Theoretical Proposal ◽  
Domain Of Validity ◽  
Simple Dependence

The Time-dependent Ginzburg–Landau model (TDGLM) is a robust tool widely used to analyze the magnetization of the single-vortex state of a mesoscopic superconducting sample in presence of a magnetic field. The algorithm implemented in this work is applied to a square geometry surrounded by different kinds of materials simulated by deGennes extrapolation length . The inside of the sample remains at constant temperature , while its boundary remains at temperature . This temperature variation in the sample can be generated by a continuous laser wave injected into all the internal points, except for a thin surface layer in the boundary of the material. We found that the b value at , which mimics the magnetization curve for a corresponding , presents a linear dependence with the temperature. Therefore, although within the domain of validity TDGLM the parameter  is to be considered temperature-independent in the vicinity of the bulk critical temperature and that  depends on the density of states near the surface, we propose a simple dependence of using a TDGLM.

scholarly journals Dimer structure as topological pinning center in a superconducting sample

2020 ◽  
Vol 19 (1) ◽  
pp. 109-115 ◽  
Author(s):  
Cristian A Aguirre ◽  
MiryamR. Joya ◽  
J. Barba-Ortega
Keyword(s):  
Magnetic Field ◽  
Pulsed Laser ◽  
Vortex State ◽  
Vortex Matter ◽  
Ginzburg Landau ◽  
Pinning Centers ◽  
Dimer Structure ◽  
Ginzburg Landau Equations ◽  
Superconducting Sample ◽  
Pinning Center

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

Ginzburg–Landau theory of the Abrikosov vortex state near the upper critical field

1982 ◽  
Vol 60 (3) ◽  
pp. 299-303 ◽  
Author(s):  
A. E. Jacobs
Keyword(s):  
Critical Field ◽  
Landau Theory ◽  
Upper Critical Field ◽  
Vortex State ◽  
Quantization Condition ◽  
Abrikosov Vortex ◽  
Ginzburg Landau ◽  
Type Ii Superconductors ◽  
Flux Quantization ◽  
The Magnetic Field

A method which preserves the flux-quantization condition in all orders of perturbation theory is applied to the Ginzburg–Landau theory of type-II superconductors near the upper critical field. Expansions are obtained for the order parameter, the magnetic field, and the free energy; previous results are verified and extended to one higher order in Hc2 – Ha.

scholarly journals Ultra-fast kinematic vortices in mesoscopic superconductors: the effect of the self-field

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Leonardo Rodrigues Cadorim ◽  
Alexssandre de Oliveira Junior ◽  
Edson Sardella
Keyword(s):  
Characteristic Curve ◽  
Vortex Street ◽  
Resistive State ◽  
Ginzburg Landau ◽  
Normal Contact ◽  
Material Inhomogeneity ◽  
Mesoscopic Superconductors ◽  
Ginzburg Landau Equations ◽  
Superconducting Sample ◽  
Sample Width

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.

THE TOPOLOGICAL STRUCTURE OF SINGLE VORTEX IN THE FF STATE

2011 ◽  
Vol 25 (26) ◽  
pp. 2041-2051
Author(s):  
XINLE SHANG ◽  
PENGMING ZHANG ◽  
WEI ZUO
Keyword(s):  
Magnetic Field ◽  
Applied Magnetic Field ◽  
Topological Structure ◽  
Single Vortex ◽  
Ginzburg Landau ◽  
The Core ◽  
The Magnetic Field

In this paper, we study the coexistence of the vortex and the FF state by using the generalized Ginzburg–Landau (GL) functional with the applied magnetic field, and obtain the numeric solutions. Furthermore, we investigate the topological structure of the vortex and find that the property of vortices relies heavily on the modulation q along z-axis. There is no topological vortex when q < qp, and the value [Formula: see text] is more favorable for the topological vortex. Moreover the magnetic field at the core of the vortex is obtained for the topological vortex.

QUANTUM SUPERCONDUCTING FLUCTUATIONS AND DISSIPATION IN VORTEX STATES

1996 ◽  
Vol 10 (06) ◽  
pp. 601-634 ◽  
Author(s):  
RYUSUKE IKEDA
Keyword(s):  
Phase Diagram ◽  
Vortex Flow ◽  
Mean Field ◽  
Feynman Graph ◽  
Transition Line ◽  
Single Vortex ◽  
Ginzburg Landau ◽  
Vortex States ◽  
Resistance Curves ◽  
Superconducting Fluctuations

Quantum effects on renormalized superconducting fluctuations are studied in the context of vortex states. It is argued by taking account of existing resistivity data that inclusion of dissipative (metallic) dynamics is indispensable at any nonzero temperature. Analysis is largely based on simple extensions of the usual time-dependent Ginzburg–Landau (TDGL) dynamics to quantum regime. First, phase diagram and dc conductivities resulting from a quantum GL action with purely dissipative dynamics are investigated, and it is noticed that, on (or, in the vicinity of) the transition line between the vortex lattice and the resulting quantum vortex liquid regime, the inverse of vortex flow conductance becomes a nearly universal value of the order of R q = 6.45 ( k Ω) and independent of material parameters. On the other hands, based on the usual Feynman graph analysis of Kubo formula, the superconducing (i.e. fluctuation) contribution to dc diagonal conductance decreases upon cooling in the disordered phase affected by quantum fluctuations, and becomes zero in T = 0 liquid regime [and above Hc2 (0)] irrespective of the details of dynamics. Reflecting these theoretical results, calculated resistance curves show the behavior quite similar to those observed in homogeneously disordered thin films, even though the presence of a field-tuned insulator–superconductor transition at T = 0 is neglected and the dynamics is purely dissipative. Phenomena in systems with quantum fluctuation of moderate strength are also considered. Analysis is also extended to the cases with other dynamical terms. It is pointed out that the usual (mean field) vortex flow Hall conductivity is never found in any nondissipative T = 0 liquid regime, and argued that, in general, the superconducting Hall effect itself is absent there at low enough fields irrespective of the presence of particle–hole assymmetry. Therefore, in contrast to the thermal vortex states with no pinning disorder, the dc transport phenomena at T = 0 are quite sensitive to the corresponding phase diagram, and hence, discussions based on the single vortex dynamics are even qualitatively invalid in the liquid regime at extremely low temperatures.

scholarly journals Vortex guide under a Lorentz force

2020 ◽  
pp. 101-106
Author(s):  
C. A. Aguirre ◽  
Q. Martins ◽  
Jose Barba
Keyword(s):  
Magnetic Field ◽  
Magnetic Susceptibility ◽  
External Magnetic Field ◽  
Lorentz Force ◽  
Vortex State ◽  
Cooper Pairs ◽  
Magnetic Response ◽  
External Current ◽  
Critical Temperatures ◽  
Ginzburg Landau

In the present work we studied the effect of the nature of the contacts, by which a weak external current is applied, in an anisotropic superconducting rectangle, on the magnetization, magnetic susceptibility, density of the Cooper pairs and  (magnetic field for which the first vortices entry on the sample). The contacts are simulates by the  parameter, and the anisotropy is present in sections with different critical temperatures modeling for  function, both in the Ginzburg-Landau formalis. Also, the sample is embebbed in an external magnetic field . We established how the nature of the contacts and the presence of a weak Lorentz Force, influence the magnetic response and the vortex state of the sample.

scholarly journals Transforming understanding of paleomagnetic recording: Insights from experimental observations of laboratory aged thermal remanences

2020 ◽  
Author(s):  
Lisa Tauxe ◽  
Christeanne Santos ◽  
Xiang Zhao ◽  
Andrew Roberts
Keyword(s):  
Magnetic Field ◽  
Domain Walls ◽  
Vortex State ◽  
Estimation Methods ◽  
Zero Field ◽  
Ideal Behavior ◽  
Temperature Spectrum ◽  
Single Vortex ◽  
Thermal Origin ◽  
The Stability

&lt;p&gt;Ne&amp;#769;el theory (doi: 10.1080/0001873550010120 ) predicts that natural remanent magnetizations (NRMs) of thermal origin will be nearly linearly related to the magnetic field in which they are acquired for field strenghts as low as the Earth's. This makes it in principle possible to estimate the strength of ancient magnetic fields. In practice, however, recovering the ancient field strength is complicated. The simple theory only pertains to uniformly magnetized (single domain, SD particles). While SD theory predicts that a magnetization acquired at a temperature T should be demagnetized by zero-field reheating to T, yet failure of this &amp;#8220;reciprocity&amp;#8221; requirement has long been observed and the causes and consequences for grains with no domain walls are unknown. Recent experiments (Shaar and Tauxe, doi: 10.1073/pnas.1507986112 and Santos and Tauxe, doi:10.1029/2018GC007946) have demonstrated that, in contrast to the stability of SD remanences over time, the remanence in many paleomagnetic samples typically used in paleointensity experiments are unstable, exhibiting an &quot;aging&quot; effect in which the unblocking temperature spectrum changes over only a few years.&amp;#160; This behavior is completely unexpected from theory. Solving these mysteries is key to cracking the problem of paleointensity estimation. In this presentation we will demonstrate that it is a shift in unblocking temperatures observed over even relatively short time intervals (two years) in certain samples that leads to the failure of reciprocity which in turn limits the ability to acquire accurate and precise estimates of the ancient magnetic field. From rock magnetic experiments (xFORCs) it seems likely that magnetic grains larger than the highly stable single vortex state are the source of the non-ideal behavior. This non-ideal behavior which leads to differences between known and estimated fields that can be rather large (up to 10 &amp;#956;T) for individual specimens, does appear to lead to a bias in field estimates.&amp;#160; It is unclear how this behavior can be compensated for using the most common paleointensity estimation methods.&amp;#160; &amp;#160;&lt;/p&gt;

Calorimetric properties of a superconducting anisotropic square: ZFC process

2020 ◽  
pp. 2150128
Author(s):  
C. A. Aguirre ◽  
Q. D. Martins ◽  
J. Barba-Ortega
Keyword(s):  
Specific Heat ◽  
Free Energy Density ◽  
Vortex State ◽  
Cooper Pairs ◽  
Zero Field ◽  
Cooling Process ◽  
Ginzburg Landau ◽  
Ginzburg Landau Equations ◽  
Zero Field Cooling

We analyzed the role of the inclusion of anti-dots on the vortex state and some calorimetric properties of a mesoscopic superconducting square immersed in an external applied magnetic field. We calculated the magnetization, entropy, Gibbs free energy, density of Cooper pairs and specific heat for this system in a zero field cooling process, solving the time-dependent Ginzburg–Landau equations. We found that the critical temperature is non-dependent on the number of anti-dots and dependent slightly on the size of the defects. Oscillations in the entropy and specific heat are found due the temperature dependence of the superconducting characteristics length.

Building the Electrical Model of the Photoelectric Laser Stimulation of an NMOS Transistor in 90 nm Technology

2012 ◽  
Author(s):  
A. Sarafianos ◽  
R. Llido ◽  
O. Gagliano ◽  
V. Serradeil ◽  
M. Lisart ◽  
...  
Keyword(s):  
Physical Simulation ◽  
Spot Size ◽  
Electrical Model ◽  
Continuous Laser ◽  
Nmos Transistor ◽  
Carrier Generation ◽  
Laser Stimulation ◽  
Laser Wave ◽  
Spatial Parameters ◽  
Physical Insight

Abstract This paper presents the electrical model of an NMOS transistor in 90nm technology under 1064nm Photoelectric Laser Stimulation. The model was built and tuned from measurements made on test structures and from the results of physical simulation using Finite Element Modeling (TCAD). The latter is a useful tool in order to understand and correlate the effects seen by measurement by given a physical insight of carrier generation and transport in devices. This electrical model enables to simulate the effect of a continuous laser wave on an NMOS transistor by taking into account the laser’s parameters (i.e. spot size and power), spatial parameters (i.e. the spot location and the NMOS’ geometry) and the NMOS’ bias. It offers a significant gain of time for experiment processes and makes it possible to build 3D photocurrent cartographies generated by the laser on the NMOS, in order to predict its response independently of the laser beam location.

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