  Magnanite multilayers have been fabricated using La0.67Ca0.33MnO3 as the
ferromagnetic layer and Pr0.7Ca0.3MnO3 and Nd0.5Ca0.5MnO3 as the spacer layers.
All the multilayers were grown on LaAlO3 (100) by pulse laser deposition. An
enhanced magnetoresistnace (defined (RH- R0)/R0) of more than 98% is observed
in these multilayers. Also a low field magnetoresistance of 41% at 5000 Oe is
observed in these multilayer films. The enhanced MR is attributed to the
induced double exchange in the spacer layer, which is giving rise to more
number of conducting carriers. This is compared by replacing the spacer layer
with LaMnO3 where Mn exists only in 3+ state and no enhancement is observed in
the La0.67Ca0.33MnO3 / LaMnO3 multilayers as double exchange mechanism can not
be induced by external magnetic fields.
