Vortex dynamics in nano-scaled superconducting complex structures (d-dot)

Using the finite element method, we have solved the time-dependent Ginzburg-Landau equation for nano-scaled composite structures with s- and d-wave superconductors, which are called d-dots. Our result shows the external current can cause the transition between two degenerate flux states of the d-dot. We have examined the time dependence of the free energy of the d-dot system during this transition and confirmed the free energy has a double-well shape. Also, we show the transition time as a function of the external current.