Thin superconducting (SC) strips of width comparable to the coherence length exhibit magnetoresistance oscillations when subject to a perpendicular magnetic field B at low temperatures T [1]. In particular, the transition into the insulator at a critical field Bc is preempted by several consecutive transitions at lower fields. To investigate this phenomenon, we have studied a quasi one-dimensional (1D) model for the quantum dynamics of vortices in a line-junction between coupled parallel SC wires, at parameters close to their superconductor-insulator transition. Refermionization is applied to map the vortices onto 1D Fermions at a chemical potential dictated by B. We find that a quantum phase transition of the Ising type occurs at critical values of the vortex filling from a SC phase close to integer filling to an insulator close to 1/2-filling. The resistance of the double--wire system is evaluated as a function of B and T, yielding magnetoresistance oscillations similar to the experimental observation in strip-like samples.

References

[1] A. Johansson, G. Sambandamurthy, N. Jacobson, D. Shahar, and R. Tenne, Phys. Rev. Lett. 95, 116805 (2005).