Intergranular Tunnelling and Field-Induced Percolation Fluctuation of Granular Composites (La1-zAgzMnO3)/(MnO2/Mn2O3)
ZHANG Ning1, BAO Jian-Chun2, LI Gang3, GENG Tao4, CHEN Ji-Kang1
1Department of Physics, Nanjing Normal University, Nanjing 210097
2Department of Chemistry, Nanjing Normal University, Nanjing 210097
3Center of Measurement and Analysis, Nanjing Normal University, Nanjing 210097
4Department of Physics, University of Shanghai for Science and Technology, Shanghai 200000
Intergranular Tunnelling and Field-Induced Percolation Fluctuation of Granular Composites (La1-zAgzMnO3)/(MnO2/Mn2O3)
1Department of Physics, Nanjing Normal University, Nanjing 210097
2Department of Chemistry, Nanjing Normal University, Nanjing 210097
3Center of Measurement and Analysis, Nanjing Normal University, Nanjing 210097
4Department of Physics, University of Shanghai for Science and Technology, Shanghai 200000
Abstract： We investigate the giant magnetoresistance of composites (La1-zAgzMnO3)1-y(MnO2/Mn2O3)y. The magnetoresistive property of the composites shows the characteristics of intergranular tunnelling. A conductivity leap has been observed around y=0.7. The composite (La0.926Ag0.074MnO3)0.698(MnO2/Mn2O3)0.302 has been found to show the greatest magnetoresistance in the samples. Its room-temperature MR ratio reaches 24% under a field of 1.8T. These phenomena suggest a percolation transformation and a kind of field-induced fluctuation in percolation in the samples investigated.
2005, Vol. 22 
