  Thin films of the iron-based superconductor BaFe2(As1-xPx)2 (Ba122:P) were
fabricated on polycrystalline metal-tape substrates with two kinds of in-plane
grain boundary alignments (well aligned (4 deg.) and poorly aligned (8 deg.))
by pulsed laser deposition. The poorly aligned substrate is not applicable to
cuprate-coated conductors because the in-plane alignment >4 deg. results in
exponential decay of the critical current density (Jc). The Ba122:P film
exhibited higher Jc at 4 K when grown on the poorly aligned substrate than on
the well-aligned substrate even though the crystallinity was poorer. It was
revealed that the misorientation angles of the poorly aligned samples were less
than 6 deg., which are less than the critical angle of an iron-based
superconductor, cobalt-doped BaFe2As2 (~9 deg.), and the observed strong
pinning in the Ba122:P is attributed to the high-density grain boundaries with
the misorientation angles smaller than the critical angle. This result reveals
a distinct advantage over cuprate-coated conductors because well-aligned
metal-tape substrates are not necessary for practical applications of the
iron-based superconductors.
