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 (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.