Synthesis and magnetoresistance properties of La2/3Ca1/3MnO3/MgO core-shell nanocomposites

In this work, (1-x)La_2/3Ca_1/3MnO₃(LCMO)/xMgO (x=0, 0.1, 0.2, 0.3, 0.4, 1) core-shell composite particles were first synthesized by a polyacrylamide gel route, and then the obtained composite particles were pelletized and sintered into the bulk composite samples. It is believed that the MgO phase was self welded to form a three-dimensional-connectivity matrix and the LCMO particles were discretely embedded in the MgO matrix without adhesion. The magnetoresistance (MR) properties of the composite samples were investigated. It is demonstrated that the MR value increases with raising MgO concentration x at low temperatures (T<;80 K), and also the low-field sensitivity of MR, defined as d(MR)/dff, gets enhanced for the composites. The enhancement in MR can be attributed to the enhanced spin polarized tunneling of conduction electrons at the grain boundaries in the composite samples.