Enhancement of magnetoresistance in manganite multilayers

Manganite multilayers have been fabricated using La0.67Ca0.33MnO3 as the fe rromagnetic layer and Pr0.7Ca0.3MnO3 and Nd0.5Ca0.5MnO3 as the spacer layer s. 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 magnetoresis tance is attributed to the induced double exchange in the spacer layer, whi ch 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 field s.