Temperature features of magnetoresistance of layered manganite La2Sm0.4Sr0.6Mn2O7

Abstract: Bulk polycrystalline layered perovskite sample La2Sm0.4Sr0.6Mn2O7 was prepared by the conventional solid-state reaction technique. Temperature dependence of magnetization measurements in the zero-field-cooled and field-cooled conditions with an applied magnetic field of 100Oe indicates that layered manganite La2Sm0.4Sr0.6Mn2O7 undergoes a paramagnetic to ferromagnetic transition at Curie temperature T c∼355K. The magnetic transition temperature (T c) is much higher than metal–insulator transition temperature (T p) obtained from temperature dependence resistivity measurement. The anisotropic exchange interaction may be one of the reasons resulting in a large deviation between T c and T p. Field dependence of magnetization measurements showed a high value of magnetization (62emu/g at 5K and 42emu/g at 300K) in an applied magnetic field of 1T. At 78K, a sharp increase of magnetoresistance was observed at low magnetic fields followed by a weak and linear dependence at high fields. [Copyright &y& Elsevier]