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无机材料学报

无机材料学报

• 研究论文 • 上一篇    下一篇

颗粒表面覆Cu的La2/3Ca1/3MnO3复合颗粒系统中的低场高磁电阻效应

袁松柳; 方重华; 缪菊红; 刘胜; 夏正才   

  1. 华中科技大学物理系, 武汉 430074
  • 收稿日期:2004-04-05 修回日期:2004-05-10 出版日期:2005-05-20 网络出版日期:2005-05-20

Large Magnetoresistance under a Low Applied Magnetic Field in a Cu-dependent Material Coated-La2/3Ca1/3MnO3 Granular System

YUAN Song-Liu; FANG Chong-Hua; MIAO Ju-Hong; LIU Sheng; XIA Zheng-Cai   

  1. Department of Physics; Huazhong University of Science and Technology; Wuhan 430074; China
  • Received:2004-04-05 Revised:2004-05-10 Published:2005-05-20 Online:2005-05-20

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摘要： 用化学方法将Cu有关的材料引入到La2/3Ca1/3MnO3颗粒表面以形成复合颗粒系统.低磁场(0.3T)下磁电阻与温度关系测量表明,伴随着Cu有关材料的引入,磁电阻图像发生了明显变化.对纯La2/3Cal/3MnO3颗粒系统,磁电阻随温度降低而单调增加;而对复合颗粒系统,磁电阻最明显的特征是绝缘体-金属转变温度附近表现出尖的磁电阻峰,且有较高的磁电阻值.结合低场磁化实验对实验结果进行了讨论.

关键词: 铁磁金属颗粒, 自旋极化隧穿, 低场磁电阻, 庞磁电阻

Abstract: A composite granular system consisting of La2/3Ca1/3MnO3 grains and Cu-dependent material,
introduced into the boundary region of the granular surface, was fabricated in a chemical route. The measurement of magnetoresistance $versus$ temperature
dependence for a low magnetic field (0.3 T) indicates that the features of magnetoresistance in the composite granular system are significantly different
from that in pure La2/3Ca1/3MnO3. The pure La2/3Ca1/3MnO3 granular system shows a monotonic increasing response in magnetoresistance
with cooling. But for the composite granular system, a sharp peak with large magnetoresistance appears in the magnetoresistance versus temperature curve
at a temperature near which the insulator-metal transition occurs. The experimental observation was discussed based on the measurement of low-field
magnetization.

Key words: ferromagnetic metallic granular system, spin-polarized tunneling, low-field magnetoresistance, colossal magnetoresistance

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