Critical current of a granular d-wave superconductor

The twist angle γ dependence of the Josephson critical current of d-wave superconductors in one junction and a granular system is considered. Our results show that the twist angle γ dependence of the d-wave Josephson critical current is the same for one junction and a granular system. The magnetic field dependences of the critical-current of a granular d-wave superconductor has also been determined by considering the rectangular and circular junction model of an array of small superconducting particles which interacting by Josephson coupling through insulating barriers. We will show that in the case of circular model, the critical current of the Josephson current is larger than that of rectangular one.