  Much smoother surfaces and significantly improved superconducting properties
of relatively thick YBa2Cu3O7 (YBCO) films have been achieved by introducing a
multilayered structure with alternating main YBCO and additional NdBCO layers.
The surface of thick (1 microm) multilayers has almost no holes compared to
YBCO films. Critical current density (Jc) have been drastically increased up to
a factor > 3 in 1 microm multilayered structures compared to YBCO films over
entire temperature and applied magnetic filed range. Moreover, Jc values
measured in thick multilayers are even larger than in much thinner YBCO films.
The Jc and surface improvement have been analysed and attributed to growth
conditions and corresponding structural peculiarities.
