Enhancement of magnetoresistance in manganite multilayers

Abstract

Manganite multilayers have been fabricated using La_0.67Ca_0.33MnO₃ as the ferromagnetic layer and Pr_0.7Ca_0.3MnO₃ and Nd_0.5Ca_0.5MnO₃ as the spacer layers. All the multilayers were grown on LaAlO₃ (100) by pulse laser deposition. An enhanced magnetoresistance (defined (R_H-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 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 La_0.67Ca_0.33MnO₃/LaMnO₃ multilayers as a double exchange mechanism cannot be induced by external magnetic fields.