Critical velocity of a clean one-dimensional superconductor

Tzu-Chieh Wei; Paul M. Goldbart

doi:10.1103/PhysRevB.80.134507

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Critical velocity of a clean one-dimensional superconductor

Tzu-Chieh Wei, Paul M. Goldbart

DOI 10.1103/PhysRevB.80.134507 · Physical Review B

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Abstract

We revisit the problem of critical velocity of a clean one-dimensional superconductor. At the level of mean-field theory, we find that the zero-temperature value of the critical velocity—the uniform velocity of the superfluid condensate at which the superconducting state becomes unstable—is a factor of 2 smaller than the Landau critical velocity. This is in contrast to a prior finding, which held that the critical velocity is equal to the Landau critical velocity. The smaller value of the critical velocity, which our analysis yields, is the result of a pre-emptive Clogston-Chandrasekhar-type discontinuous phase transition, and is an analog of the threshold value of the uniform exchange field of a superconductor previously investigated by Sarma [J. Phys. Chem. Solids 24, 1029 (1963)] and by Maki and Tsuneto [Prog. Theor. Phys. 31, 945 (1964)]. We also consider the impact of nonzero temperature, study critical currents, and examine metastability and its limits in the temperature versus flow-velocity phase diagram. In addition, we comment on the effects of electron scattering by impurities.