High-field Josephson effect caused by the inside-grain vortices

We present a theoretical prediction of the new effects for critical currents across single grain boundaries in polycrystalline superconductors being under an applied magnetic field. It was shown that Josephson oscillation should be observed not only in the case of the increasing of the magnetic flux through the junction but also when vortex penetrates inside grain. In the intergrain Josephson junction the critical transport current is strongly dependent on the normalized grain size ratio, grain anisotropy ratio and grain coupling strength. These results imply that achieving a high degree of texture along these parameters is important for the obtaining of very high critical currents in pure polycrystalline samples. Also, it is shown that in contrast to the well-known Fraunhofer dependence, the period of oscillations corresponds to adding flux quantums per two grains.