1208.1964 (Shi-Zeng Lin et al.)

Dissociation of composite vortex lattice in two-band superconductors in
the flux-flow state    [PDF]

Shi-Zeng Lin, Lev N. Bulaevskii

In multiband superconductors, each superconducting condensate supports vortices with fractional quantum flux. In the ground state, vortex in different bands is spatially bounded together to form a composite vortex, carrying one quantum flux $\Phi_0$. Here we predict dissociation of the composite vortices lattice in the flux flow state due to the disparity of vortex viscosity and flux of the vortex in different bands. For a small driving current, the composite vortices starts to deform, but the constituting vortices in different bands move with the same velocity. For a large current, composite vortices dissociate and vortices in different bands move with different velocities. The dissociation transition shows up as increase of flux flow resistivity. In the dissociated phase, Shapiro steps are developped when an ac current is superimposed with a dc current.

View original: http://arxiv.org/abs/1208.1964