Abstract :
Polycrystalline Sm1.4Sr1.2Ca0.4Mn2O7 has been successfully synthesized and investigated with respect to its magnetic and electrical properties. It is found that the sample shows a metal insulator (M–I) transition at 88 K. The maxima of the magnetoresistance (MR) ratio are 95.38% and 98.55% under applied fields of 2 T and 5 T, respectively. At 10 K, the MR attains ∼75% at 5 T. The large MR at low temperature can be attributed to the effects of nearly fully spin-polarized carriers tunneling through the insulating (Sm, Sr, Ca)2O2 layers between the adjacent MnO2 bi-layers. The magnetization data indicates the existence of ferromagnetic clusters.
