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By using the full 3D generalized time-dependent Ginzbug-Landau equation, we study a long superconducting film of finite width and thickness under an applied transport current. We show that, for sufficiently large thickness, the vortices and the antivortices become curved before they annihilate each other. As they approach the center of the sample, their ends combine, producing a single closed vortex. We also determine the critical values of the thickness for which the closed vortex sets in for different values of the Ginzburg-Ladau parameter. Finally, we propose a model of how to detect a closed vortex experimentally.

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., Comment: 9 pages, 6 figures. Accepted for publication in Scientific Reports

Studies involving vortex dynamics and their interaction with pinning centers are an important ingredient to reach higher critical currents in superconducting materials. The vortex distribution around arrays of engineered defects, such as blind and through holes, may help to improve the superconducting properties. Thus, in this work, we used the time-dependent Ginzburg-Landau theory to investigate the vortex dynamics in superconductors of mesoscopic dimensions with a large central square defect with three different configurations: (i) a hole which passes through the sample (interface with the vacuum); (ii) a superconducting region with lower critical temperature (Tc); and (iii) a region with a more robust superconductivity, i.e., with a higherTc. Such systems can be envisaged as elementary building blocks of a macroscopic decorated specimen. Therefore, we evaluated the influence of different interfaces on the vortex dynamics and their effects in the field-dependent magnetization and time-dependent induced electric potential variation. The results show that the lower critical field is independent from the nature of the defect. However, the currents crowd at the vertices of the through hole producing a lower degradation of the local superconductivity, which may increase the upper critical field. On the other hand, the last type of defect can be used to control the vortex dynamics in the main superconducting region around the defect with more accuracy. Whereas the first two defects are attractive for the vortices, the third type is repulsive for them, being needed several vortices penetrated in the superconducting matrix to have vortices penetrated into it., Comment: 14 pages, 8 figures, preprint version

In the description of non equilibrium situations in a superconductor at temperatures far below its critical temperature, the Keldysh-Usadel technique (KUT) is required. However, the non-stationary KUT has not been applied to realistic circuits. Moreover, the stationary KUT has been applied in situations where time independence is not guaranteed. As a plausibility check for this procedure, we resort to a toy model (the Ginzburg-Landau model), in situations that involve very slow evolution. We find that, even in these situations, neglecting the explicit influence of time variation leads to inaccurate or even qualitatively wrong description of phase slips., Co-author joined

The generalized time-dependent Ginzburg-Landau (GTDGL) theory was first proposed to describe better gap superconductors and the phenomenon of thermal phase-slips (PSs) in defect-free systems. However, there is a lack of information about studies involving PSs in mesoscopic superconductors with surface defects. Thus, in this work, we simulated samples with two co-linear surface defects consisting of a lower $T_c$ superconductor narrowing the sample in its central part. The non-linear GTDGL equations were solved self-consistently under variable applied currents and by considering both gapless and gap-like superconductors. In such systems, the currents passing by the constriction induce the appearance of kinematic vortices even in the gapless sample. The dynamics always occur with a pair forming at opposite edges of the sample and annihilating in the center. It is noticed that the resistive state appears at distinct values of the applied current density for different samples, and the critical current presents a tiny difference between gapless and gap-like samples. It is worth mentioning that parameters such as the size of electrical contacts and constriction affect the critical current and the average velocity of the kinematic vortices., Comment: 7 pages, 15 figures, submitted to Physics Letters A

Made available in DSpace on 2019-10-06T15:31:19Z (GMT). No. of bitstreams: 0 Previous issue date: 2019-03-15 We consider a mesoscopic superconducting three-dimensional cube immersed in a tilted magnetic field H oriented along an angle θ with respect to the z-axis, in the xz plane. The sample is in contact with a metallic material or with another superconductor in the xz and yz planes, while the z=0 plane remains in contact with a dielectric material. These boundary conditions are simulated by the de Gennes extrapolation length b. We analyzed the magnetic induction, the superconducting electron density, and the magnetization curves as functions of H for different values of b on the lateral surfaces of the sample. We show that the magnetization and the vortex configuration depend on θ and b. An analytical linear and exponential dependence of the maximum of the magnetization on θ and b, respectively, was found. Departamento de Física Universidad Nacional de Colombia Departamento de Física Universidade Estadual Paulista UNESP Departamento de Física Universidade Estadual Paulista UNESP

Submitted by Leonardo Rodrigues Cadorim (leonardo.cadorim@unesp.br) on 2021-06-28T22:38:40Z No. of bitstreams: 1 Clusters_of_vortices_induced_by_thermal_gradient_in_mesoscopic_superconductors.pdf: 1288743 bytes, checksum: 7b2fb5d4e586c8524ec90aa9419d263b (MD5) Approved for entry into archive by Lucilene Cordeiro da Silva Messias null (lubiblio@bauru.unesp.br) on 2021-07-13T13:48:17Z (GMT) No. of bitstreams: 1 cadorim_lr_versaofinaldoeditor_bauru_clusters.pdf: 1288743 bytes, checksum: 7b2fb5d4e586c8524ec90aa9419d263b (MD5) Made available in DSpace on 2021-07-13T13:48:17Z (GMT). No. of bitstreams: 1 cadorim_lr_versaofinaldoeditor_bauru_clusters.pdf: 1288743 bytes, checksum: 7b2fb5d4e586c8524ec90aa9419d263b (MD5) Previous issue date: 2021-05-26 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) The structural and magnetic properties of the vortex matter in mesoscopic superconductors have been of great interest in the last decades. Recently, it has been found that vortex-vortex interaction, which is generally repulsive, can be non-monotonic under some special circumstances. Here, we have studied this issue by applying the three dimensional time dependent Ginzburg-Landau equations to a thin type-I mesoscopic superconducting film under a thermal gradient. We find that this favors the formation of small clusters of vortices in some special domains of the superconductor. We also find that this is intimately related to the non-monotonic vortex-vortex interaction by investigating the behavior of two constrained vortices in the presence of a thermal gradient. We show that the vortex-vortex interaction alternates between short range attraction and long range repulsion. This study shows that the thermal gradient has the potential to be an important tool to manipulate the vortex matter. Departamento de Física, Faculdade de Ciências, Universidade Estadual Paulista (UNESP), Caixa Postal 473, 17033-360, Bauru-SP, Brazil Departamento de Física e Química, Faculdade de Engenharia de Ilha Solteira, Universidade Estadual Paulista (UNESP), Caixa Postal 31, 15385-000 Ilha Solteira-SP, Brazil FAPESP: 20/03947-2 FAPESP: 19/24618-0 FAPESP: 20/10058-0

M. Tinkham and P. G. de Gennes, described in their books the existence of an intermediate type-I superconductor as a consequence of an external surface that affects the well known classification of superconductors into type-I and II. Here we consider the mesoscopic superconductor where the ratio volume to area is small and the effects of the external surface are enhanced. By means of the standard Ginzburg-Landau theory the Tinkham-de Gennes scenario is extended to the mesoscopic type-I superconductor. We find new features of the transition at the passage from the genuine to the intermediate type-I. The latter has two distinct transitions, namely, from a paramagnetic to diamagnetic response in descending field and a quasi type-II behavior as the critical coupling is approached in ascending field. The intermediate type-I phase proposed here, and its corresponding transitions, reflect intrinsic features of the superconductor and not its geometrical properties., Accepted for publication in Physical Review B. 6 pages, 4 figures

Made available in DSpace on 2020-12-12T02:22:22Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-10-14 In this work, we studied the dynamics of the kinematic vortices (kV) in a mesoscopic superconductor under the influence of external applied magnetic fields (H) and transport currents (J tr). A J tr(H) phase diagram is determined. We show that the vortex dynamics are profoundly affected by the presence of constrictions and by H. We find that between the Meissner and normal states, the resistive state is comprehended by three distinct states. One of these states is a kinematic vortex-antivortex pair for low values of H. For moderate values of fields, the kV state is unpaired and only a single kinematic vortex exists. In the high field regime, the kinematic vortex becomes an Abrikosov-like state with a lower velocity. It was also shown that for tenths of picoseconds, a surface barrier effect acts over the instantaneous velocity of the kV. Departamento de Física e Química Unesp Faculdade de Engenharia de Ilha Solteira Departamento de Física Unesp Faculdade de Ciências Departamento de Física e Química Unesp Faculdade de Engenharia de Ilha Solteira Departamento de Física Unesp Faculdade de Ciências

Made available in DSpace on 2021-06-25T11:18:05Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-08-06 Fundação de Amparo à Ciência e Tecnologia do Estado de Pernambuco Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro (FAPERJ) We study here the spike state found in mesoscopic type I superconductors whose existence is confined to the single field where the superconducting state arises from the normal state in descending field in the so-called genuine type I regime. The mesoscopic type I superconductor possesses distinct κ regimes due to its richer critical field structure Cadorim et al. (2021) [11]. The lifetime of the spike state is shown to be in the nanosecond scale through the time dependent Ginzburg-Landau (TDGL) equations. The spike state is a giant vortex state that undergoes a process of deformation after its creation when several bubbles of vortices are expelled forming new but deformed giant vortices until no one is left inside the superconductor. Like phase slips and kinematic vortices, the spike state is also a non-equilibrium vortex state. Departamento de Física Universidade Federal Rural do Rio de Janeiro UFRRJ Departamento de Física Faculdade de Ciências Universidade Estadual Paulista (UNESP), Caixa Postal 473 Departamento de Física Universidade Federal Rural de Pernambuco UFRPE Instituto de Física Universidade Federal do Rio de Janeiro UFRJ Departamento de Física Faculdade de Ciências Universidade Estadual Paulista (UNESP), Caixa Postal 473 FAPESP: 20/03947-2 FAPESP: 20/10058-0 CAPES: 88887.494140/2020-00 CAPES: APQ-0198-1.05/14 FAPERJ: E-26/010.001497/2019

The Ginzburg-Landau theory, applied to superconducting materials is based on thermo-magneto-electro-dynamic concepts as phase transitions that enrich the class on this subject. Thus, in this contribution we expose the Ginzburg-Landau time-dependent equations, show the mathematical form for two nano-scale superconducting systems, one bi-dimensional homogeneous al sample with applied external current at zero magnetic field, and one three-dimensional cube in presence of a tilted magnetic fiel at zero applied current. This analysis shows the applicability of the three and two-dimensional model to superconductors. The conveniently Ginzburg-Landau theory show that the magnetic response behavior of the sample is very useful for applications in fluxtronica, SQUIDS design, magnetic resonance, among others.

Made available in DSpace on 2019-10-04T12:39:09Z (GMT). No. of bitstreams: 0 Previous issue date: 2019-07-01 We study the resistive state of a mesoscopic superconducting strip with an engineered defect at the center. The defect is another superconductor with a different critical temperature. Several geometrical shapes of the defect are studied. The strip is considered under a transport electrical current, J(a), and at zero external applied magnetic field. The current is applied through a metallic contact, and the defect is simulated with the phenomenological parameter (T) = (0)(T - T-c(r)) in the Ginzburg-Landau free energy density. Here T-c(r) = T-c,T-0 + T(r), where T(r) < 0 (T(r) > 0) corresponds to a domain of lower (higher) critical temperature. It is shown that the critical current density for the I-V characteristic curve, J(c1), at which the first vortex-antivortex (V-Av) pair nucleates in the sample, as well as its dynamics, strongly depend on the critical temperature, the position, and the geometry of the defect. Univ Nacl Colombia, Dept Fis, Bogota, Colombia Univ Estadual Paulista, Dept Fis, Fac Ciencias, Caixa Postal 473, BR-17033360 Bauru, SP, Brazil Univ Estadual Paulista, Dept Fis, Fac Ciencias, Caixa Postal 473, BR-17033360 Bauru, SP, Brazil

Made available in DSpace on 2020-12-10T19:53:01Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-02-01 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) We study the superconducting state of a strip under an transport current J(a) and an external magnetic field H. We show that the value of the critical currents at which the vortex-antivortex (V-Av) pair penetrates the sample, the number of phase-slip lines, and their average velocities and dynamics strongly depend on the size of the sample L. Our investigation was carried out by numerically solving the two-dimensional generalized time-dependent Ginzburg-Landau equations (GTDGL). Univ Fed Mato Grosso, Dept Fis, Cuiaba, Brazil Univ Estadual Paulista, Dept Fis, Bauru, SP, Brazil Univ Nacl Colombia, Dept Fis, Bogota, Colombia Univ Estadual Paulista, Dept Fis, Bauru, SP, Brazil CAPES: 089.229.701-89

Studies with mesoscopic superconducting materials have made significant advances on the last decades. One of the applications of such systems is in devices for single photon and single electron detectors. However, depending on the geometry of these systems, crowding current effects take place and, as a consequence, the total critical current could decrease which facilitates the penetration of vortices. This effect could also be responsible for a variety of penetration morphologies of flux avalanches in macroscopic samples. Thus, in this work we used the time-dependent Ginzburg-Landau theory to study the crowding current effects in mesoscopic superconducting systems with an array of antidots. It is demonstrated that the profile of the currents is influenced by the antidots, i.e., in the vertices of the antidots the intensity of the currents increases. On the other hand, the profile of the currents in between the antidots is more affected in the smaller system which presents closer antidots., 4 pages, 4 figures, presented on ASC 2014 and submitted to IEEE TRANSACTION ON APPLIED SUPERCONDUCTIVITY

We theoretically investigate the local magnetic field, order parameter and supercurrent profiles of a parallelepiped mesoscopic superconductor submersed in an applied magnetic field; this same geometry with a pillar on its top surface is also considered. Our investigation was carried out by solving the three-dimensional time-dependent Ginzburg–Landau (TDGL) equations. We obtain the magnetization curve as a function of the external applied magnetic field for several sample sizes. We have determined an analytical dependence of the thermodynamic fields and the magnetization as functions of the lateral dimension of the superconductor. Finally, a systematic comparative study of the two- and three-dimensional approaches of the Ginzburg–Landau model is carried out.

Made available in DSpace on 2018-12-11T17:16:06Z (GMT). No. of bitstreams: 0 Previous issue date: 2018-01-30 Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) We studied the resistive state of a mesoscopic superconducting strip (bridge) at zero external applied magnetic field under a transport electric current, Ja, subjected to different types of boundary conditions. The current is applied through a metallic contact (electrode) and the boundary conditions are simulated via the deGennes extrapolation length b. It will be shown that the characteristic current–voltage curve follows a scaling law for different values of b. We also show that the value of Ja at which the first vortex–antivortex (V–Av) pair penetrates the sample, as well as their average velocities and dynamics, strongly depend on the b values. Our investigation was carried out by solving the two-dimensional generalized time dependent Ginzburg–Landau (GTDGL) equation. Grupo de Física Mesoscópica Departamento de Física Universidad Nacional de Colombia Departamento de Física Universidade Estadual Paulista (UNESP) Faculdade de Ciências, Caixa Postal 473 Departamento de Física e Química Universidade Estadual Paulista (UNESP) Faculdade de Engenharia de Ilha Solteira, Caixa Postal 31 Departamento de Física Universidade Estadual Paulista (UNESP) Faculdade de Ciências, Caixa Postal 473 Departamento de Física e Química Universidade Estadual Paulista (UNESP) Faculdade de Engenharia de Ilha Solteira, Caixa Postal 31 FAPESP: 2012/04388-0 FAPESP: 2016/12390-6

The manipulation and control of vortex states in superconducting systems are of great interest in view of possible applications, for which mesoscopic materials are good candidates. In this work, we studied the annihilation dynamics and the dissipative aspects of an Abrikosov's vortex-antivortex pair in a mesoscopic superconducting system with a concentric hole. The generalized time-dependent Ginzburg-Landau equations were numerically solved. The main result is the appearance of a phase slip-like line due to the elongation of the vortex and antivortex cores. Under specific circumstances, thermal dissipation might be associated with a sizeable relaxation of the order parameter, so that the energy released in the annihilation of a vortex-antivortex pair might become detectable in measurements of the magnetization as a function of time., actual file 16 pages, 11 figures

Using the nonlinear Ginzburg–Landau equations we study the vortex configurations in a superconducting square with a central square pillar in the presence of a uniform applied magnetic field. The presence of the pillar changes the vortex structure in the superconducting sample considerably. We calculate magnetization, magnetic induction, supercurrent and vorticity, which show different vortex configurations as a function of magnetic field.

The influence of the different negative values of the deGennes parameter $$b$$ in the thermodynamic properties of a superconducting infinitely long prism of square cross section area $$S=9\xi ^{2}(0)$$ in the presence of a magnetic field is investigated theoretically by solving numerically the nonlinear Ginzburg-Landau equations; $$\xi (0)$$ is the coherent length at zero temperature. We obtain the vorticity, magnetic induction, Cooper pair density, magnetization and phase of the order parameter as functions of the external applied magnetic field and the $$b$$ parameter. Our results show that a multi-vortex state appear in the sample choosing a convenient value of $$b

Submitted by Leonardo Rodrigues Cadorim (leonardo.cadorim@unesp.br) on 2021-06-28T21:47:07Z No. of bitstreams: 1 Crossover_from_type_I_to_type_II_regime_of__mesoscopic_superconductors_of_the_first_group.pdf: 3584053 bytes, checksum: 81ad486033427a74ea41e0cd8c591347 (MD5) Rejected by Lucilene Cordeiro da Silva Messias null (lubiblio@bauru.unesp.br), reason: Favor refazer a submissão seguindo as orientações abaixo: 1 - Indicar o prazo de restrição do acesso ao documento no Repositório. Se há restrição, obrigatoriamente deve-se indicar a data. 2 - Ao enviar um artigo que já foi publicado em um Periódico, verificar se a Revista permite a publicação do material em outro meio. Agradecemos a compreensão on 2021-06-30T13:59:40Z (GMT) Submitted by Leonardo Rodrigues Cadorim (leonardo.cadorim@unesp.br) on 2021-06-30T17:04:33Z No. of bitstreams: 1 Crossover_from_type_I_to_type_II_regime_of__mesoscopic_superconductors_of_the_first_group.pdf: 3584050 bytes, checksum: b04f666db17377ed12614123793258cf (MD5) Approved for entry into archive by Lucilene Cordeiro da Silva Messias null (lubiblio@bauru.unesp.br) on 2021-07-13T15:06:06Z (GMT) No. of bitstreams: 1 cadorim_lr_versaofinaldoeditor_bauru_crossover.pdf: 3584050 bytes, checksum: b04f666db17377ed12614123793258cf (MD5) Made available in DSpace on 2021-07-13T15:06:06Z (GMT). No. of bitstreams: 1 cadorim_lr_versaofinaldoeditor_bauru_crossover.pdf: 3584050 bytes, checksum: b04f666db17377ed12614123793258cf (MD5) Previous issue date: 2019-12-02 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) In the present work, we have studied the crossover between type I and type II superconductivity on mesoscopic superconducting thin films by numerically solving the 3D Ginzburg-Landau equations. We determined the dependence on temperature of the critical Ginzburg-Landau parameter kc(d), below which the superconductor behaves as type I for a given thickness d of the film. The effect of the sample dimensions on this crossover was also investigated. Additionally, we report a novel giant vortex configuration with a local minimum of the magnetic field at the centre of the core. Finally, we present certain results suggesting that the vortex-vortex interaction is not monotonic, varying instead from long-range attraction to short-range repulsion Departamento de Física, Faculdade de Ciências, Universidade Estadual Paulista (UNESP), Caixa Postal 473, 17033-360, Bauru-SP, Brazil Departamento de Física e Química, Faculdade de Engenharia de Ilha Solteira, Universidade Estadual Paulista (UNESP), Caixa Postal 31, 15385-000 Ilha Solteira-SP, Brazil FAPESP: 20/03947-2

Made available in DSpace on 2019-10-06T16:43:50Z (GMT). No. of bitstreams: 0 Previous issue date: 2019-07-11 Usually, the measurements of electronic and magnetic properties of superconducting samples are carried out under a constant temperature bath. On the other hand, thermal gradients induce local variation of the superconducting order parameter, and the vortex dynamics can present interesting behaviors. In this work, we solved the time-dependent Ginzburg-Landau equations simulating samples under two different thermal gradients, and considering two values of the Ginzburg-Landau parameter, κ. We find that both parameters, i.e. κ and thermal gradients, play an important role on the vortex dynamics and on the magnetization behavior of the samples. Departamento de Física e Química Faculdade de Engenharia de Ilha Solteira Universidade Estadual Paulista (UNESP), Caixa Postal 31 Departamento de Física Faculdade de Ciências Universidade Estadual Paulista (UNESP), Caixa Postal 473 Departamento de Física e Química Faculdade de Engenharia de Ilha Solteira Universidade Estadual Paulista (UNESP), Caixa Postal 31 Departamento de Física Faculdade de Ciências Universidade Estadual Paulista (UNESP), Caixa Postal 473

Made available in DSpace on 2019-10-06T17:05:15Z (GMT). No. of bitstreams: 0 Previous issue date: 2019-01-01 We investigate the self-assembly of vortices in a type-II superconducting disk subjected to highly nonuniform confining potentials produced by inhomogeneous magnetic textures. Using a series of numerical experiments performed within the Ginzburg-Landau theory, we show that vortices can arrange spontaneously in highly nonuniform, defect-free crystals, reminiscent of conformal lattices, even though the strict conditions for the conformal crystal are not fulfilled. These results contradict continuum-limit theory, which predicts that the order of a nonuniform crystal is unavoidably frustrated by the presence of topological defects. By testing different cooling routes of the superconductor, we observed several different self-assembled configurations, each of which corresponding to one in a set of allowed conformal transformations, which depends on the magnetic and thermal histories of the system. Departamento de Física Universidade Federal de Pernambuco Cidade Universitária Departamento de Física Faculdade de Ciências Universidade Estadual Paulista-UNESP, Caixa Postal 473 Departamento de Física Faculdade de Ciências Universidade Estadual Paulista-UNESP, Caixa Postal 473

We study the influence of a pentagonal (hexagonal) trench or barrier on the superconducting properties of a perforated disk. Effects associated to the pinning (anti-pinning) force of the central hole and the trench (barrier) and the interplay between the boundary conditions and the shape of the inner defects on the vortex configuration are studied for a thin disk. Also, we considered two cases for the value of the order parameter at the surface. The first one is ψ s ≠0; this is the usual supercondutor/vacuum interface, for which the deGennes parameter is b→∞. The second one is ψ s =0, which is the surface of the sample in a complete normal state, simulated by b=0. The vorticity, Gibbs free energy, magnetic induction, supercurrent density, magnetization and Cooper pairs density as a function of the external magnetic field are calculated. We show that in our sample new phenomena are possible due to the competing interactions of the boundary and the geometry of the sample and the added geometry of the nanoengineered trench and barrier.

The vortex matter in a superconducting disk with a linear configuration of metallic and superconducting defects is studied. Effects associated to the pinning (anti-pinning) force of the metallic (superconducting) defect on the vortex configuration and on the thermodynamic critical fields are analyzed in the framework of the Ginzburg Landau theory. We calculate the loop of the magnetization, vorticity and free energy curves as a function of the magnetic field for a thin disk. Due to vortex–defect attraction for a metallic defect (repulsion for a superconducting defect), the vortices always (never) are found to be sitting on the defect position.

By solving the time dependent Ginzburg–Landau equations, we investigated the influence of an internal triangular arrangement of point-like defects on the vortex configurations in a thin mesoscopic sample. The effect of the number of internal defects and their nature on the entrance position of the vortex is studied for a very thin circular sample. We found that the interplay between the vortex–vortex repulsion, the vortex–defect interaction and the interaction with the sample border leads to non-commensurate vortex configurations.

In this paper we study the formation of vortices in a mesoscopic superconducting segment ring. We evaluate the magnetization, superconducting to normal magnetic field transition and the superconductor density of electrons. Our results point out that, as we reduce the superconducting segment width, remaining its area constant, both the first and third critical fields increases. Also, the third critical field exhibits a typical behavior as function of the angular width Θ of the segment ring, namely, the curve H C 3 ( Θ ) decreases monotonically with increasing the angle width and diverges in the limit Θ → 0 . In addition, we have found an analytical expression from the magnetization as a function of the segment width.

In this paper we study some superconducting properties of a flat disk by taking into account the roughness of the surface. Also, the sample is surrounded by a thin layer of a metallic material and submitted to and external magnetic field applied perpendicular to its plane. The boundary condition is taking into account via the de Gennes extrapolation length b. We evaluate the Gibbs free energy, magnetization, vorticity, the first and second critical thermodynamical fields as a function of the external magnetic field and b parameter. We also evaluate the first critical field as a function of the surface rugosity.

Nonlinear time-dependent Ginzburg–Landau (TDGL) equations were solved in the present work using the link variables method. Vortex configurations were investigated in a superconducting circular sector immersed in an external magnetic field applied perpendicular to its plane. Magnetization and free energy were calculated as a function of the applied magnetic field at several temperatures. This paper illustrates how the vortices moved around at the transition fields before they become accommodated into an equilibrium configuration. A linear dependence of the magnetization dependence on temperature has been found for a certain magnetic field.

In this work, we investigated theoretically the dynamics of the annihilation of a vortex–antivortex pair in a superconducting mesoscopic prism of square transversal section with a square antidot inserted at its center. The sample is immersed in a magnetic field applied perpendicular to the sample plane. It is assumed that the inner hole is made of a material whose properties are accounted on de Gennes boundary conditions via de Gennes extrapolation length (b parameter). We analyze the nucleation of vortices and antivortices by increasing the magnetic field from zero until the first vortex is created and then reversing the polarity of the applied magnetic field until an antivortex is also created. Depending on the b parameter, the vortex–antivortex encounter can take place at the hole or at the superconducting region around it. In the framework of the time dependent Ginzburg–Landau theory, we calculate the magnetization, order parameter topology, the position and the velocity of the vortex and antivortex singularities as a function of time.

In this paper we apply the time dependent Ginzburg–Landau (TDGL) equations to the study of thin superconducting films of variable surfaces in the presence of an external applied magnetic field. We have made a systematic investigation of both the lower and upper critical fields as a function of the topological parameters which control the shape of the film surfaces. We also make a detailed investigation of the vortex dynamics as they nucleate into the sample.

We investigate the superconducting states that arise as a consequence of mesoscopic confinement and a multi-component order parameter in the Ginzburg-Landau model for $p\,$-wave superconductivity. Conventional vortices, but also half-quantum vortices and skyrmions are found as the applied magnetic field and the anisotropy parameters of the Fermi surface are varied. The solutions are well differentiated by a topological charge that for skyrmions is given by the Hopf invariant and for vortices by the circulation of the superconducting velocity. We revealed several unique states combining vortices and skyrmions, their possible reconfiguration with varied magnetic field, as well as the novel temporal and field-induced transitions between vortical and skyrmionic states., 14 pages, 14 figures

Made available in DSpace on 2018-12-11T16:59:02Z (GMT). No. of bitstreams: 0 Previous issue date: 2015-12-18 We consider a mesoscopic superconducting parallelepiped with different boundary conditions on different parts of the surface, xy, xz and yz surface planes. This is realized by considering different values of the de Gennes extrapolation length b on different surfaces of the sample. Our investigation was carried out by solving the three-dimensional (3D) time dependent Ginzburg-Landau (TDGL) equations. We studied the local magnetic field, order parameter, and both the magnetization and vorticity curves as functions of the external applied magnetic field for different values of b on the surfaces of the sample. We show that this surface anisotropy has very strong influence on the vortex configurations and the magnetization as a function of the external applied magnetic field, both experimentally accessible. Departamento de F�sica Universidad Nacional de Colombia UNESP-Universidade Estadual Paulista Departamento de F�sica, Caixa Postal 473 UNESP-Universidade Estadual Paulista IPMet-Instituto de Pesquisas Meteorol�gicas, CEP 17048-699 UNESP-Universidade Estadual Paulista Departamento de F�sica, Caixa Postal 473 UNESP-Universidade Estadual Paulista IPMet-Instituto de Pesquisas Meteorol�gicas, CEP 17048-699

In the present work we study the influence of the surface on the vortex structure as a function of the sample size for different temperatures. It is shown that a crossover between a hexagonal lattice, which is characteristic of the macroscopic samples, and a square lattice occurs in the vicinity of a threshold line which delimits the macro and the mesoscopic superconducting regimes, L c ( T ). Such study was carried out by computational simulations where we used the time dependent Ginzburg–Landau equations in the discretized form.

The study of superconducting samples in mesoscopic scale presented a remarkable improvement during the last years. Certainly, such interest is based on the fact that when the size of the samples is close to the order of the temperature dependent coherence length ξ(T) and/or the size of the penetration depth λ(T), there are some significant modifications on the physical properties of the superconducting state. This contribution tests the square cross-section size limit for the occurrence (or not) of vortices in mesoscopic samples of area L2, where L varies discretely from 1ξ(0) to 8ξ(0). The time dependent Ginzburg–Landau (TDGL) equations approach is used upon taking the order parameter and the local magnetic field invariant along the z-direction. The vortex configurations at the equilibrium can be obtained from the TDGL equations for superconductivity as the system relaxes to the stationary state. The obtained results show that the limit of vortex penetration is for the square sample of size 3ξ(0)×3ξ(0) in which only a single vortex are allowed into the sample. For smaller specimens, no vortex can be formed and the field entrance into the sample is continuous and the total flux penetration occurs at higher values of H/Hc2(0), where Hc2(T) is the upper critical field. Otherwise, for larger samples different vortices patterns can be observed depending on the sample size.

The presence of barriers changes the vortex structure in superconducting Nb square in presence of a uniform applied magnetic field. The Cooper pair configurations in a mesoscopics superconducting square of Nb with a barrier are calculated within the nonlinear Ginzburg Landau equations. We predict the nucleation of multi-vortex states into the sample and a soft entry of the magnetic field inside and around into the barrier. A novel and non-conventional vortex configurations occurs at determined magnetic field.

The time-dependent Ginzburg-Landau formalism for (d + s)-wave superconductors and their representation using auxiliary fields is investigated. By using the link variable method, we then develop suitable discretization of these equations. Numerical simulations are carried out for a mesoscopic superconductor in a homogeneous perpendicular magnetic field which revealed peculiar vortex states. (C) 2014 AIP Publishing LLC.

We considered a system of two vortex lines running in different directions with their average vortex direction making an arbitrary angle θ with respect to the crystal c axis. The free energy of this system is calculated as a function of the relative angle 2α between the two inclined vortex lines with respect to each other. For sufficiently high anisotropy, it is shown that, as the induction is tilted away from the crystal c axis (θ ≠ 0), the inclined vortex lines (α ≠ 0) suddenly becomes more stable than that with parallel vortex lines (α = 0). While θ increased, the system continuously changes towards the parallel configuration before the angle θ approaches 90°.

In this work we solved the time-dependent Ginzburg-Landau equations, TDGL, to simulate two superconducting systems with different lateral sizes and with an antidot inserted in the center. Then, by cycling the external magnetic field, the creation and annihilation dynamics of a vortex-antivortex pair was studied as well as the range of temperatures for which such processes could occur. We verified that in the annihilation process both vortex and antivortex acquire an elongated format while an accelerated motion takes place., 4 pages, 5 figures, work presented in Vortex VIII

In this work we solved the time dependent Ginzburg-Landau equations to simulate homogeneous superconducting samples with square geometry for several lateral sizes. As a result of such simulations we notice that in the Meissner state, when the vortices do not penetrate the superconductor, the response of small samples are not coincident with that expected for the bulk ones, i.e., $4\pi M=-H$. Thus, we focused our analyzes on the way which the $M(H)$ curves approximate from the characteristic curve of bulk superconductors. With such study, we built a diagram of the size of the sample as a function of the temperature which indicates a threshold line between macroscopic and bulk behaviors., Comment: 6 pages, 5 figures

Submitted by Vitor Silverio Rodrigues (vitorsrodrigues@reitoria.unesp.br) on 2014-05-27T11:18:05Z No. of bitstreams: 0Bitstream added on 2014-05-27T14:38:37Z : No. of bitstreams: 1 2-s2.0-0039746413.pdf: 167404 bytes, checksum: cabf51a13f491ee2c5c6578aaf6ea9ff (MD5) Submitted by Vitor Silverio Rodrigues (vitorsrodrigues@reitoria.unesp.br) on 2014-05-27T11:18:05Z No. of bitstreams: 0Bitstream added on 2014-05-27T14:38:37Z : No. of bitstreams: 1 2-s2.0-0039746413.pdf: 167404 bytes, checksum: cabf51a13f491ee2c5c6578aaf6ea9ff (MD5) Made available in DSpace on 2014-05-27T11:18:05Z (GMT). No. of bitstreams: 0 Previous issue date: 1996-06-01 Made available in DSpace on 2014-05-27T11:18:05Z (GMT). No. of bitstreams: 0 Previous issue date: 1996-06-01 Submitted by Vitor Silverio Rodrigues (vitorsrodrigues@reitoria.unesp.br) on 2014-05-27T11:18:05Z No. of bitstreams: 0Bitstream added on 2014-05-27T14:38:37Z : No. of bitstreams: 1 2-s2.0-0039746413.pdf: 167404 bytes, checksum: cabf51a13f491ee2c5c6578aaf6ea9ff (MD5) Made available in DSpace on 2014-05-27T11:18:05Z (GMT). No. of bitstreams: 0 Previous issue date: 1996-06-01 Submitted by Vitor Silverio Rodrigues (vitorsrodrigues@reitoria.unesp.br) on 2014-05-27T11:18:05Z No. of bitstreams: 0Bitstream added on 2014-05-27T14:38:37Z : No. of bitstreams: 1 2-s2.0-0039746413.pdf: 167404 bytes, checksum: cabf51a13f491ee2c5c6578aaf6ea9ff (MD5) Made available in DSpace on 2014-05-27T11:18:05Z (GMT). No. of bitstreams: 0 Previous issue date: 1996-06-01 Made available in DSpace on 2014-05-27T11:18:05Z (GMT). No. of bitstreams: 0 Previous issue date: 1996-06-01 Made available in DSpace on 2014-05-27T11:18:05Z (GMT). No. of bitstreams: 0 Previous issue date: 1996-06-01 Made available in DSpace on 2014-05-27T11:18:05Z (GMT). No. of bitstreams: 0 Previous issue date: 1996-06-01 Made available in DSpace on 2014-05-27T11:18:05Z (GMT). No. of bitstreams: 0 Previous issue date: 1996-06-01 Two distinct expressions of the interaction potential between arbitrarily oriented curved vortex lines with respect to the crystal c axis are derived within the London approximation. One of these expressions is used to compute the eigenvalues of the elasticity matrix. We examine the elastic properties of the vortex chain lattice, recently proposed, concerning shearing deformation. Departamento de Física Universidade Estadual Paulista, Caixa Postal 473, 17033-360, Bauru-SP Departamento de Física Universidade Estadual Paulista, Caixa Postal 473, 17033-360, Bauru-SP

The influence of superficial defects on the vortex configurations of a thin superconducting disk is investigated within the time dependent Ginzburg-Landau formalism. The free energy, magnetization, vorticity, and the Cooper pair density are calculated for both metastable and stable vortex configurations and different number of defects on its surface in the presence of an external magnetic field applied perpendicular to the disk area. We show that the competition between the confinement geometry and the geometric position of the defects leads to non-conventional vortex configurations which are not compatible with the symmetry of the sample geometry. Crown Copyright (C) 2013 Published by Elsevier B.V. All rights reserved.

Made available in DSpace on 2022-04-29T02:57:34Z (GMT). No. of bitstreams: 0 Previous issue date: 2012-06-11 In the present work we report the existence of a crossover between the macroscopic and mesoscopic regimes of vortex interactions in type-II superconductors. Our findings rely on a systematic procedure to determine this crossover, which is based on the influence of the surface on the vortex structure of small superconductors. An adjacent result that we have found is that near this regime transformation, the vortex lattice develops a progressive change of symmetry, from square to hexagonal, which is intimately related to the meso-to-macro crossover. Our numerical simulations have been done for a long superconducting cylinder of square cross section for a wide range of length scales and temperatures. © 2012 American Physical Society. Faculdade de Engenharia de Ilha Solteira Universidade Estadual Paulista Departamento de Física e Química, Caixa Postal 31, 15385-000, Ilha Solteira, São Paulo Universidade Estadual Paulista Instituto de Pesquisas Meteorológicas, CEP 17048-699 Bauru, São Paulo Universidade Estadual Paulista Departamento de Física Faculdade de Ciências, Caixa Postal 473, 17033-360, Bauru, São Paulo Departamento de Física Universidade Federal de São Carlos, 13565-905, São Carlos, São Paulo Centre for Advanced Study Norwegian Academy of Science and Letters, NO-0271, Oslo Faculdade de Engenharia de Ilha Solteira Universidade Estadual Paulista Departamento de Física e Química, Caixa Postal 31, 15385-000, Ilha Solteira, São Paulo Universidade Estadual Paulista Instituto de Pesquisas Meteorológicas, CEP 17048-699 Bauru, São Paulo Universidade Estadual Paulista Departamento de Física Faculdade de Ciências, Caixa Postal 473, 17033-360, Bauru, São Paulo

Made available in DSpace on 2022-04-29T08:44:10Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-08-06 The dynamics of the annihilation of a vortex-antivortex pair is investigated. The pair is activated magnetically during the run of a simulated hysteresis loop on a square mesoscopic superconducting cylinder with an antidot inserted at its center. We study the nucleation of vortices and antivortices by first increasing the magnetic field, applied parallel to the axis of the sample, from zero until the first vortex is created. A further increase in the field pulls the vortex in, until it reaches the antidot. As the polarity of the field is reversed, an antivortex enters the scene, travels toward the center of the sample, and eventually the pair is annihilated. Depending on the sample size, its temperature, and Ginzburg-Landau parameter, the vortex-antivortex encounter takes place at the antidot or at the superconducting sea around it. The position and velocity of the vortex and antivortex singularities were evaluated as a function of time. The current density, magnetization, and order-parameter topology were also calculated. © 2009 The American Physical Society. Departamento de Física Faculdade de Ciências Caixa Postal 473, 17033-360 Bauru, SP Departamento de Física Universidade Federal de Pernambuco, 50670-901 Recife, PE Departamento de Física Universidade Federal de São Carlos, 13565-905 São Carlos, SP

In the present paper we develop an algorithm to solve the time dependent Ginzburg-Landau (TDGL) equations, by using the link variables technique, for circular geometries. In addition, we evaluate the Helmholtz and Gibbs free energy, the magnetization, and the number of vortices. This algorithm is applied to a circular sector. We evaluate the superconduting-normal magnetic field transition, the magnetization, and the superconducting density. Furthermore, we study the nucleation of giant and multi-vortex states for that geometry., Comment: One REVTeX file and 8 figures

Made available in DSpace on 2022-04-28T20:08:16Z (GMT). No. of bitstreams: 0 Previous issue date: 2006-07-27 In this work we investigate the dynamics of vortices in a square mesoscopic superconductor. As time evolves we show how the vortices are nucleated into the sample to form a multivortex, single vortex, and giant vortex states. We illustrate how the vortices move around at the transition fields before they accommodate into an equilibrium configuration. We also calculate the magnetization and the free energy as functions of the applied magnetic field for several values of temperature. In addition, we evaluate the upper critical field. © 2006 The American Physical Society. Departamento de Física Faculdade de Ciências Universidade Estadual Paulista-UNESP, Caixa Postal 473, 17033-360, Bauru-SP Departamento de Física Universidade Federal de São Carlos-UFSCar, Caixa Postal 676, 13566-905, São Carlos-SP Departamento de Física Faculdade de Ciências Universidade Estadual Paulista-UNESP, Caixa Postal 473, 17033-360, Bauru-SP

Submitted by Guilherme Lemeszenski (guilherme@nead.unesp.br) on 2013-08-22T19:01:23Z No. of bitstreams: 1 S0103-97332004000600018.pdf: 127044 bytes, checksum: 95a535c09426f8a87d31755f2b68d181 (MD5) Made available in DSpace on 2013-08-22T19:01:23Z (GMT). No. of bitstreams: 1 S0103-97332004000600018.pdf: 127044 bytes, checksum: 95a535c09426f8a87d31755f2b68d181 (MD5) Previous issue date: 2004-09-01 Made available in DSpace on 2013-09-30T20:01:22Z (GMT). No. of bitstreams: 2 S0103-97332004000600018.pdf: 127044 bytes, checksum: 95a535c09426f8a87d31755f2b68d181 (MD5) S0103-97332004000600018.pdf.txt: 12748 bytes, checksum: 41dbfef66df67a718a7c8e15a33e3daa (MD5) Previous issue date: 2004-09-01 Submitted by Vitor Silverio Rodrigues (vitorsrodrigues@reitoria.unesp.br) on 2014-05-20T15:15:42Z No. of bitstreams: 2 S0103-97332004000600018.pdf: 127044 bytes, checksum: 95a535c09426f8a87d31755f2b68d181 (MD5) S0103-97332004000600018.pdf.txt: 12748 bytes, checksum: 41dbfef66df67a718a7c8e15a33e3daa (MD5) Made available in DSpace on 2014-05-20T15:15:42Z (GMT). No. of bitstreams: 2 S0103-97332004000600018.pdf: 127044 bytes, checksum: 95a535c09426f8a87d31755f2b68d181 (MD5) S0103-97332004000600018.pdf.txt: 12748 bytes, checksum: 41dbfef66df67a718a7c8e15a33e3daa (MD5) Previous issue date: 2004-09-01 In the present paper we consider the vortex lattice properties of a square superconductor such as the vortex patterns, the Gibbs free energy, the magnetization, and the depairing critical current density. We show that this last quantity shows a matching effect, that is, it shows a discontinuous behavior as a function of the applied magnetic field. Universidade Estadual Paulista Faculdade de Ciências Departamento de Física Universidade Estadual Paulista Faculdade de Ciências Departamento de Física

In the present work we investigate the behavior of a vortex in a long superconducting cylinder near to a columnar defect at the center. The derivations of the local magnetic field distribution and the Gibbs free energy will be carried out for a cylinder and a cavity of arbitrary sizes. From the general expressions, it considered two particular limits: one in which the radius of the cavity is very small but the radius of the superconducting cylinder is kept finite; and one in which the radius of the superconducting cylinder is taken very large (infinite) but the radius of the cavity is kept finite. In both cases the maximum number of vortices which are allowed in the cavity is determined. In addition, the surface barrier field for flux entrance into the cavity is calculated., 13 pages, 1 figure

Submitted by Guilherme Lemeszenski (guilherme@nead.unesp.br) on 2013-08-22T19:01:20Z No. of bitstreams: 1 S0103-97332002000400005.pdf: 225586 bytes, checksum: 87a3bae2a5545f6b882d75ed3263cb20 (MD5) Submitted by Guilherme Lemeszenski (guilherme@nead.unesp.br) on 2013-08-22T19:01:20Z No. of bitstreams: 1 S0103-97332002000400005.pdf: 225586 bytes, checksum: 87a3bae2a5545f6b882d75ed3263cb20 (MD5) Made available in DSpace on 2013-08-22T19:01:20Z (GMT). No. of bitstreams: 1 S0103-97332002000400005.pdf: 225586 bytes, checksum: 87a3bae2a5545f6b882d75ed3263cb20 (MD5) Previous issue date: 2002-09-01 Submitted by Guilherme Lemeszenski (guilherme@nead.unesp.br) on 2013-08-22T19:01:20Z No. of bitstreams: 1 S0103-97332002000400005.pdf: 225586 bytes, checksum: 87a3bae2a5545f6b882d75ed3263cb20 (MD5) Made available in DSpace on 2013-08-22T19:01:20Z (GMT). No. of bitstreams: 1 S0103-97332002000400005.pdf: 225586 bytes, checksum: 87a3bae2a5545f6b882d75ed3263cb20 (MD5) Previous issue date: 2002-09-01 Made available in DSpace on 2013-09-30T20:01:15Z (GMT). No. of bitstreams: 2 S0103-97332002000400005.pdf: 225586 bytes, checksum: 87a3bae2a5545f6b882d75ed3263cb20 (MD5) S0103-97332002000400005.pdf.txt: 9930 bytes, checksum: d351acc56b59e2080c14f41307345f46 (MD5) Previous issue date: 2002-09-01 Made available in DSpace on 2013-09-30T20:01:15Z (GMT). No. of bitstreams: 2 S0103-97332002000400005.pdf: 225586 bytes, checksum: 87a3bae2a5545f6b882d75ed3263cb20 (MD5) S0103-97332002000400005.pdf.txt: 9930 bytes, checksum: d351acc56b59e2080c14f41307345f46 (MD5) Previous issue date: 2002-09-01 Made available in DSpace on 2013-08-22T19:01:20Z (GMT). No. of bitstreams: 1 S0103-97332002000400005.pdf: 225586 bytes, checksum: 87a3bae2a5545f6b882d75ed3263cb20 (MD5) Previous issue date: 2002-09-01 Made available in DSpace on 2013-08-22T19:01:20Z (GMT). No. of bitstreams: 1 S0103-97332002000400005.pdf: 225586 bytes, checksum: 87a3bae2a5545f6b882d75ed3263cb20 (MD5) Previous issue date: 2002-09-01 Submitted by Vitor Silverio Rodrigues (vitorsrodrigues@reitoria.unesp.br) on 2014-05-20T15:15:40Z No. of bitstreams: 2 S0103-97332002000400005.pdf: 225586 bytes, checksum: 87a3bae2a5545f6b882d75ed3263cb20 (MD5) S0103-97332002000400005.pdf.txt: 9930 bytes, checksum: d351acc56b59e2080c14f41307345f46 (MD5) Submitted by Vitor Silverio Rodrigues (vitorsrodrigues@reitoria.unesp.br) on 2014-05-20T15:15:40Z No. of bitstreams: 2 S0103-97332002000400005.pdf: 225586 bytes, checksum: 87a3bae2a5545f6b882d75ed3263cb20 (MD5) S0103-97332002000400005.pdf.txt: 9930 bytes, checksum: d351acc56b59e2080c14f41307345f46 (MD5) Made available in DSpace on 2014-05-20T15:15:40Z (GMT). No. of bitstreams: 2 S0103-97332002000400005.pdf: 225586 bytes, checksum: 87a3bae2a5545f6b882d75ed3263cb20 (MD5) S0103-97332002000400005.pdf.txt: 9930 bytes, checksum: d351acc56b59e2080c14f41307345f46 (MD5) Previous issue date: 2002-09-01 Made available in DSpace on 2013-09-30T20:01:15Z (GMT). No. of bitstreams: 2 S0103-97332002000400005.pdf: 225586 bytes, checksum: 87a3bae2a5545f6b882d75ed3263cb20 (MD5) S0103-97332002000400005.pdf.txt: 9930 bytes, checksum: d351acc56b59e2080c14f41307345f46 (MD5) Previous issue date: 2002-09-01 Submitted by Guilherme Lemeszenski (guilherme@nead.unesp.br) on 2013-08-22T19:01:20Z No. of bitstreams: 1 S0103-97332002000400005.pdf: 225586 bytes, checksum: 87a3bae2a5545f6b882d75ed3263cb20 (MD5) Made available in DSpace on 2014-05-20T15:15:40Z (GMT). No. of bitstreams: 2 S0103-97332002000400005.pdf: 225586 bytes, checksum: 87a3bae2a5545f6b882d75ed3263cb20 (MD5) S0103-97332002000400005.pdf.txt: 9930 bytes, checksum: d351acc56b59e2080c14f41307345f46 (MD5) Previous issue date: 2002-09-01 Made available in DSpace on 2013-09-30T20:01:15Z (GMT). No. of bitstreams: 2 S0103-97332002000400005.pdf: 225586 bytes, checksum: 87a3bae2a5545f6b882d75ed3263cb20 (MD5) S0103-97332002000400005.pdf.txt: 9930 bytes, checksum: d351acc56b59e2080c14f41307345f46 (MD5) Previous issue date: 2002-09-01 Made available in DSpace on 2013-08-22T19:01:20Z (GMT). No. of bitstreams: 1 S0103-97332002000400005.pdf: 225586 bytes, checksum: 87a3bae2a5545f6b882d75ed3263cb20 (MD5) Previous issue date: 2002-09-01 Submitted by Vitor Silverio Rodrigues (vitorsrodrigues@reitoria.unesp.br) on 2014-05-20T15:15:40Z No. of bitstreams: 2 S0103-97332002000400005.pdf: 225586 bytes, checksum: 87a3bae2a5545f6b882d75ed3263cb20 (MD5) S0103-97332002000400005.pdf.txt: 9930 bytes, checksum: d351acc56b59e2080c14f41307345f46 (MD5) Made available in DSpace on 2013-09-30T20:01:15Z (GMT). No. of bitstreams: 2 S0103-97332002000400005.pdf: 225586 bytes, checksum: 87a3bae2a5545f6b882d75ed3263cb20 (MD5) S0103-97332002000400005.pdf.txt: 9930 bytes, checksum: d351acc56b59e2080c14f41307345f46 (MD5) Previous issue date: 2002-09-01 Submitted by Vitor Silverio Rodrigues (vitorsrodrigues@reitoria.unesp.br) on 2014-05-20T15:15:40Z No. of bitstreams: 2 S0103-97332002000400005.pdf: 225586 bytes, checksum: 87a3bae2a5545f6b882d75ed3263cb20 (MD5) S0103-97332002000400005.pdf.txt: 9930 bytes, checksum: d351acc56b59e2080c14f41307345f46 (MD5) Made available in DSpace on 2014-05-20T15:15:40Z (GMT). No. of bitstreams: 2 S0103-97332002000400005.pdf: 225586 bytes, checksum: 87a3bae2a5545f6b882d75ed3263cb20 (MD5) S0103-97332002000400005.pdf.txt: 9930 bytes, checksum: d351acc56b59e2080c14f41307345f46 (MD5) Previous issue date: 2002-09-01 Submitted by Vitor Silverio Rodrigues (vitorsrodrigues@reitoria.unesp.br) on 2014-05-20T15:15:40Z No. of bitstreams: 2 S0103-97332002000400005.pdf: 225586 bytes, checksum: 87a3bae2a5545f6b882d75ed3263cb20 (MD5) S0103-97332002000400005.pdf.txt: 9930 bytes, checksum: d351acc56b59e2080c14f41307345f46 (MD5) Made available in DSpace on 2013-08-22T19:01:20Z (GMT). No. of bitstreams: 1 S0103-97332002000400005.pdf: 225586 bytes, checksum: 87a3bae2a5545f6b882d75ed3263cb20 (MD5) Previous issue date: 2002-09-01 Made available in DSpace on 2014-05-20T15:15:40Z (GMT). No. of bitstreams: 2 S0103-97332002000400005.pdf: 225586 bytes, checksum: 87a3bae2a5545f6b882d75ed3263cb20 (MD5) S0103-97332002000400005.pdf.txt: 9930 bytes, checksum: d351acc56b59e2080c14f41307345f46 (MD5) Previous issue date: 2002-09-01 Submitted by Vitor Silverio Rodrigues (vitorsrodrigues@reitoria.unesp.br) on 2014-05-20T15:15:40Z No. of bitstreams: 2 S0103-97332002000400005.pdf: 225586 bytes, checksum: 87a3bae2a5545f6b882d75ed3263cb20 (MD5) S0103-97332002000400005.pdf.txt: 9930 bytes, checksum: d351acc56b59e2080c14f41307345f46 (MD5) Made available in DSpace on 2014-05-20T15:15:40Z (GMT). No. of bitstreams: 2 S0103-97332002000400005.pdf: 225586 bytes, checksum: 87a3bae2a5545f6b882d75ed3263cb20 (MD5) S0103-97332002000400005.pdf.txt: 9930 bytes, checksum: d351acc56b59e2080c14f41307345f46 (MD5) Previous issue date: 2002-09-01 Made available in DSpace on 2013-09-30T20:01:15Z (GMT). No. of bitstreams: 2 S0103-97332002000400005.pdf: 225586 bytes, checksum: 87a3bae2a5545f6b882d75ed3263cb20 (MD5) S0103-97332002000400005.pdf.txt: 9930 bytes, checksum: d351acc56b59e2080c14f41307345f46 (MD5) Previous issue date: 2002-09-01 Made available in DSpace on 2014-05-20T15:15:40Z (GMT). No. of bitstreams: 2 S0103-97332002000400005.pdf: 225586 bytes, checksum: 87a3bae2a5545f6b882d75ed3263cb20 (MD5) S0103-97332002000400005.pdf.txt: 9930 bytes, checksum: d351acc56b59e2080c14f41307345f46 (MD5) Previous issue date: 2002-09-01 Made available in DSpace on 2013-09-30T20:01:15Z (GMT). No. of bitstreams: 2 S0103-97332002000400005.pdf: 225586 bytes, checksum: 87a3bae2a5545f6b882d75ed3263cb20 (MD5) S0103-97332002000400005.pdf.txt: 9930 bytes, checksum: d351acc56b59e2080c14f41307345f46 (MD5) Previous issue date: 2002-09-01 Submitted by Vitor Silverio Rodrigues (vitorsrodrigues@reitoria.unesp.br) on 2014-05-20T15:15:40Z No. of bitstreams: 2 S0103-97332002000400005.pdf: 225586 bytes, checksum: 87a3bae2a5545f6b882d75ed3263cb20 (MD5) S0103-97332002000400005.pdf.txt: 9930 bytes, checksum: d351acc56b59e2080c14f41307345f46 (MD5) Submitted by Vitor Silverio Rodrigues (vitorsrodrigues@reitoria.unesp.br) on 2014-05-20T15:15:40Z No. of bitstreams: 2 S0103-97332002000400005.pdf: 225586 bytes, checksum: 87a3bae2a5545f6b882d75ed3263cb20 (MD5) S0103-97332002000400005.pdf.txt: 9930 bytes, checksum: d351acc56b59e2080c14f41307345f46 (MD5) Made available in DSpace on 2014-05-20T15:15:40Z (GMT). No. of bitstreams: 2 S0103-97332002000400005.pdf: 225586 bytes, checksum: 87a3bae2a5545f6b882d75ed3263cb20 (MD5) S0103-97332002000400005.pdf.txt: 9930 bytes, checksum: d351acc56b59e2080c14f41307345f46 (MD5) Previous issue date: 2002-09-01 Made available in DSpace on 2014-05-20T15:15:40Z (GMT). No. of bitstreams: 2 S0103-97332002000400005.pdf: 225586 bytes, checksum: 87a3bae2a5545f6b882d75ed3263cb20 (MD5) S0103-97332002000400005.pdf.txt: 9930 bytes, checksum: d351acc56b59e2080c14f41307345f46 (MD5) Previous issue date: 2002-09-01 In the present work we study a long superconducting wire with a columnar defect in the presence of an applied magnetic field. The cross section of the cylinder is assumed to be circular. The field is taken uniform and parallel to the cylinder axis. We use the London theory to investigate the vortex lattice inside the wire. Although this theory is valid in the limit of low vortex density, that is, when the nearest neighbor vortex distance is much larger than the coherence length, we can obtain a reasonable qualitative description of lattice properties. We calculate: (1) the vortex lattice structure using the simulated annealing technique; (2) the magnetization curve as a function of the applied field. Universidade Estadual Paulista Faculdade de Ciências Departamento de Física Universidade Estadual Paulista Faculdade de Ciências Departamento de Física

In general, the studies of finite size effects in mesoscopic superconductors have been carried out in such a way that the temperature parameter is constant in the entire system. However, we could have situations where a real sample is near a heater source, as an example. In such situations, gradients of temperature are present. On the other hand, mesoscopic superconductors are interesting systems due to the fact that they present confinement effects which influence all the vortex dynamics. Thus, in this work we studied the influence of thermal gradients on the vortex dynamics in mesoscopic superconductors. For this purposes, we used the time dependent Ginzburg-Landau equations. The thermal gradients produce an asymmetric distribution of the currents around the system which, in turn, yield interesting vortex configurations and difficult the formation of giant vortices.