Growth mechanism of nanorods in REBa_2Cu_3O_y films (RE: rare-earth element)

摘要

Critical current density under magnetic fields has been improved by the introduction of artificial pinning centers. Nanorods in REBa_2Cu_3O_y films are significantly effective as c-axis-correlated pinning centers. However, nanorods sometimes tilt from the c-axis direction of superconducting films. To understand the mechanism of nanorod tilting, ErBa_2Cu_3O_y films containing Ba(Nb_(0.5)Er_(0.5))O_3 (BNO) nanorods were deposited on a SrTiO_3 single crystal with a vicinal surface. Microstructures of the nanorods were examined by transmission electron microscopy (TEM). As a result, it was found that BNO nanorods grew diagonally from steps of the substrate surface in cross-sectional TEM images. The mechanism of the diagonal growth of nanorods can be explained by the segregation coefficient.