The electronic structure of grain-boundary of YBa2Cu3O7 doped with 3d transition-metal atoms

We systemically study the electronic structures of Σ5 grain-boundary of YBa₂Cu₃O₇ with and without dopants of 3d transition-metal atoms based on the density functional theory. The partial density of states (PDOS) shows that the electronic structure of grain boundary is very different from that of crystal and the interesting orbital-reconstruction of interface is found. Generally super-current will significantly decrease when transmitting across grain boundary. The main reasons for suppressed super-current are that (1) the carriers are not uniformly distributed near grain-boundary regions and (2) the number of CuO₄-squares in CuO₂ layer, which are essentially important to transport properties, sharply decreases near grain-boundary region. The preferentially substituting sites of 3d transition-metal atoms in YBa₂Cu₃O₇ are predicted and some of them such as Co, Ni and Zn are consistent with the reported experimental analysis.