[′lən·dən ¦sü·pər‚kän‚dək′tiv·əd·ē ‚thē·ə·rē] (solid-state physics) An extension of the two-fluid model of superconductivity, in which it is assumed that superfluid electrons behave as if the only force acting on them arises from applied electric fields, and that the curl of the superfluid current vanishes in the absence of a magnetic field.