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

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 α(T) = α₀(T − T_c(r)) in the Ginzburg-Landau free energy density. Here T_c(r) = T_c,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, 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. Graphical abstract:

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