Effect of grain boundary on electrical, magnetic and magnetoresistance properties in La_2/3Ca_1/3MnO₃/CuMn₂O₄ composites

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• 作者：Pai Li ; Songliu Yuan ; Li Liu ; Xueli Wang ; Yongqiang Wang ; Zhaoming Tian ; Jinghua He ; Shijun Yuan ; Kuili Liu ; Shiyan Ying ; Chuanhui Wang
• 关键词：A. Composite materials ; C. Grain boundary ; D. Electrical transport ; D. Tunneling
• 刊名：Solid State Communications
• 出版年：2008
• 期刊代码：101_00381098
• 类别：ms
• 出版时间：June 2008
• 卷：146
• 期：11-12
• 页码：518-521
• 文件大小：677 K

摘要

Composites of La_2/3Ca_1/3MnO₃ (LCMO)/ CuMn₂O₄ were synthesized through a sol-gel method. The effect of ferrimagnetic semiconducting CuMn₂O₄ on electrical and magnetic properties has been investigated in detail. The structure analysis shows CuMn₂O₄ mainly segregates at the grain boundaries of LCMO. With the increasing content of CuMn₂O₄, the electrical transport behavior turns from T² dependent to T³ 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 CuMn₂O₄ at the grain boundaries.