Enhancement of magnetoresistance in manganite multilayers

Manganite 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 magnetoresistance (defined (R-H - R-0)/R-0) of more than 98% is observed in these multilayers. Also a low-held magnetoresistance of 41% at 5000 Oe is observed in these multilayer films. The enhanced magnetoresistance is attributed to the induced double exchange in the spacer layer, which gives rise to a greater number of conducting carriers. This is shown by replacing the spacer layer with LaMnO3 where Mn exists only in the 3+ state and no enhancement is observed in the La0.67Ca0.33MnO3/LaMnO3 multilayers as a double exchange mechanism cannot be induced by external magnetic fields.