Effect of grain boundary on electrical, magnetic and magnetoresistance properties in La2/3Ca1/3MnO3/CuMn2O4 composites

Abstract Composites of La 2/3 Ca 1/3 MnO 3 (LCMO)/ CuMn 2 O 4 were synthesized through a sol-gel method. The effect of ferrimagnetic semiconducting CuMn 2 O 4 on electrical and magnetic properties has been investigated in detail. The structure analysis shows CuMn 2 O 4 mainly segregates at the grain boundaries of LCMO. With the increasing content of CuMn 2 O 4 , the electrical transport behavior turns from T 2 dependent to T 3 dependent at low temperatures, which suggests electron–phonon and electron–magnon scattering are becoming more important. In addition, the suppression of magnetization and magnetic transition demonstrates the magnetic coupling has a sizeable influence on the composites. A significant enhancement in magnetoresistance (MR) under an applied field 0.3 T is observed over a wide temperature range, which is considered to arise from the enhanced spin-polarized tunneling caused by the addition of CuMn 2 O 4 at the grain boundaries.