Fractional magnetic flux transition in two-band single-junction superconducting rings

摘要

Based on Ginzburg-Landau (GL) theory, we study the electromagnetic properties of two-band superconducting ring with a microbridge structure. The phase difference of two-order parameters in two-band superconductors satisfies the sine-Gordon equation, and from its soliton solution, the linear relation between the phase difference at both ends of the junction and total magnetic flux in the ring can be obtained. Then with the Josephson current-phase relation in the two-band superconducting microbridge, we establish the dependence of the circulating current and total magnetic flux on the applied external magnetic field. Our analysis shows that the soliton solution and the fractional flux quantization in two-band superconductors can be verified by measuring the properties of this single-junction structure.