Resistive state of a thin superconducting strip with an engineered central defect

Abstract

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, Ja, and at zero external applied magnetic field. The current is applied through a metallic contact, and the defect is simulated with the phenomenological parameter α(T ) = α0(T − Tc(r)) in the Ginzburg-Landau free energy density. Here Tc(r) = Tc,0 + δT (r), where δT (r) < 0 (δT (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, Jc1, 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.

Memristor-like behavior and negative resistance in a superconductor/insulator/ferromagnet device with a pinholes-governed interface

“…In this context, we argue that the discrete and localized proximity effects through the pinholes play a crucial role for spatial inhomogeneities of the superconducting gap and, in turn, for the formation of islands with a suppressed superconducting order parameter. The position and the geometry of such islands can account for the observation of different types of jumps in the V(I) curves [19]. Then, one can argue that the presence of pinholes is generating regions in the superconducting Nb film where the superconducting order parameter is modified due to the magnetic proximity.…”

Diagramas de fase J1(τ) y J1(γ) de un filme superconductor

“…Podríamos intuir físicamente que haciendo más fina la malla computacional apreciaríamos que cuando se ha generado el par en el centro de la muestra, las líneas que representan la densidad de corriente que están más hacia los bordes superior e inferior, se aprecian completamente horizontales y las líneas que se encuentran cerca del centro de la muestra se verían curvadas por la cercanía con el par V-aV. Este mismo comportamiento generaría patrones de diferente densidad de corriente a medida que los vórtices van cambiando su lugar hacia los bordes de la muestra, en [26] se consideran los efectos de la geometría de defectos sobre la respuesta resistiva de películas superconductoras en presencia de corrientes, en este trabajo se relaciona que, para un defecto cuadrado no centrado, el par V-aV nuclea de forma no simétrica en la muestra debido a la asimetría de la supercorriente en la muestra y que un defecto triangular quiebra la simetría espacial para el movimiento de los pares V-aV.…”

Precursor superconducting effects in the optimally doped YBa2Cu3O7−δ superconductor: the confrontation between superconducting fluctuations and percolative effects revisited

“…As it is well known, the presence of Tc inhomogeneities can significantly alter the properties of cuprate superconductors [21,22]. The effect of a continuous 𝑇 𝑐 distribution on the resistivity can be studied through the approach proposed in Ref.…”