  We investigate the Josephson transport through ferromagnetic insulators (FIs)
by taking into account the band structure of FIs explicitly. Using the
recursive Green's function method, we found the formation of a pi-junction in
such systems. Moreover the atomic-scale 0-pi oscillation is induced by
increasing the thickness of FI and its oscillation period is universal, i.e.,
just single atomic layer. Based on these results, we show that stable pi-state
can be realized in junctions based on high-Tc superconductors with
La$_2$BaCuO$_5$ barrier. Such FI-based Josephson junctions may become an
element in the architecture of future quantum computers.
