On dissipative phenomena in the mixed superconductive state

Abstract If only very weak spatial variations of the free energy, the coherence parameter or the penetration depth occur, then the Fourier components of period equal to, or almost equal to, the period of the “mixed structure” will determine themagnitude of the critical current. At higher currents the mixed structure will slip in the direction of the Lorentz force and a resistance will appear due to electric and ultra-acoustic losses. Ultrasound should be emitted mainly as shear waves almost perpendicular to the direction of motion. In case of pronounced local irregularities “pinning of flux bundles” and local readjustment of the mixed structure will give rise to the phenomena observed and analysed by Kim and Anderson. Readjustment in large regions leads to flux jumps. Such jumps may occur when the magnetic enthalpy in certain regions has become larger than the energy in the normal state. Such flux jumps will be rare near T c , H c1 and H c2 . Annihilation of opposite fluxes may give rise to large temperature jumps.