  Artificial superlattices designed with ferromagnetic Pr0.85Ca0.15MnO3
insulating layer and ferroelectric Ba0.6Sr0.4TiO3 layer were grown on (100)
SrTiO3 substrates. The magnetotransport properties were measured with the
current perpendicular to the plane geometry. An increase in magnetoresistance
(MR), with no significant low field effect, was observed as the number of
ferroelectric Ba0.6Sr0.4TiO3 layer thickness increases even up to 9 unit cells.
For example, the superlattice [(Pr0.85Ca0.15MnO3)10(Ba0.6Sr0.4TiO3)9]25 shows
35 % MR at 100 K, though the Pr0.85Ca0.15MnO3 film was a robust insulator with
negligible MR even at high applied magnetic field. This observed large MR
cannot be explained by simple interfacial ferromagnetism or by the tunneling
magnetoresistance. One possible explanation could be the effect due to the
ferroelectric spacer layer and the associated magnetoelectric coupling.
