Control of Orientation of ${\rm RBa}_{2}{\rm Cu}_{3}{\rm O}_{7}$ Films on Substrates With Low Lattice Mismatch Via Seed Layer Formation

The orientation of high T
_c
superconducting RBa
₂
Cu
₃
O
₇
(RBCO) films is crucial for achievement of high superconducting properties. However, it is known that good lattice match between film and substrate provides favorable conditions for the growth of undesirable (100)-oriented grains in RBCO films. In this paper we demonstrate, that orientation of RBCO film is influenced not only by the mismatch, but also by substrates crystal structure. It is observed, that few nanometer thick R
₂
O
₃
(R=Nd-Gd,Y) layer on (001)SrTiO
₃
substrate effectively suppresses the formation of (100)-oriented grains in GdBCO films. To describe this behavior, a simple model based on the nucleus formation mechanism is presented.