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There is a soliton in a superconductor having two bands (two-band superconductor), when the interband interaction is much smaller than the intraband interaction. This soliton is in a stable state. In the soliton the relative phase between two gap parameters rotates 0 to 2pi (or -pi to pi), where each gap resides in each band. A phase slip of the superconducting order parameter is accompanied with the soliton. The phase slip is not nx2pi where n is an integer. A soliton traps the flux inside the superconducting ring, of which magnitude is not integral multiples of the fluxoid quantum.
Y. Tanaka (Mon,) studied this question.