  Artificial superlattices of (BiFeO3)m(SrTiO3)m (m= 1 to 10 unit cells)
consisting of multiferroic BiFeO3 and insulating SrTiO3 layers were fabricated
on (100)-oriented SrTiO3 substrates by pulsed laser ablation. The remnant
polarization and leakage current behavior were studied varying the periodicity
(8-80A) of the superlattice. The leakage current was reduced by few orders of
magnitude on increase of periodicity compared to single layer BiFeO3 thin
films. Reduced leakage and intrinsic polarization hysteresis was observed and
was confirmed by PUND analysis for periodicities in the range 20-60A. The
leakage current was observed to be dominated by space charge limited conduction
