Enhancement of magnetoresistance in manganite multilayers

Manganite multilayers have been fabricated using La 0.67 Ca 0.33 MnO 3 as the ferromagnetic layer and Pr 0.7 Ca 0.3 MnO 3 and Nd 0.5 Ca 0.5 MnO 3 as the spacer layers. All the multilayers were grown on LaAlO 3 (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-field 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 LaMnO 3 where Mn exists only in the 3+ state and no enhancement is observed in the La 0.67 Ca 0.33 MnO 3 /LaMnO 3 multilayers as a double exchange mechanism cannot be induced by external magnetic fields.