Magnitude of circulating vortex currents in the cuprates

We propose a method for determination of the circulating vortex current IQ in the high temperature superconductors. The method is based on the observation that in strongly anisotropic layered materials, the current I flowing along the weakly conducting direction can be strongly enhanced in small samples containing screw dislocations. It is shown that, although I is not quantized in units of IQ, nevertheless by means of a measurement of the phase stiffness of such samples one can determine IQ.