Current transport across grain boundary networks in high-T_c superconductors

Electric transport measurements across single grain boundaries in YBa2Cu3O7 films are summarized. These experiments demonstrate that YBa2Cu3O7 grain boundaries behave like SNS-type Josephson junctions. The implications of this weak link behavior for the critical currents of polycrystalline high-Tc superconductors are discussed in conjunction with spatially resolved measurements of the current transport in polycrystalline YBa2Cu3O7. © 1990.