中国物理B ›› 2006, Vol. 15 ›› Issue (4): 850-853.doi: 10.1088/1009-1963/15/4/032

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Simultaneous observation of positive and negative giant magnetoresistances in composite (La0.83Sr0.17MnO3)1－x(ITO)x

王淼, 张宁   

  1. Magnetoelectronic Laboratory, Nanjing Normal University, Nanjing 210097, China
  • 收稿日期:2005-12-17 修回日期:2006-01-25 出版日期:2006-04-20 发布日期:2006-04-20
  • 基金资助:
    Project supported by the National Natural Science Foundation of China (Grant No 20473038), the Foundation of High-Tech Project in Jiangsu province, China (Grant No BG-2005401).

Simultaneous observation of positive and negative giant magnetoresistances in composite (La0.83Sr0.17MnO3)1－x(ITO)x

Wang Miao (王淼), Zhang Ning (张宁)   

  1. Magnetoelectronic Laboratory, Nanjing Normal University, Nanjing 210097, China
  • Received:2005-12-17 Revised:2006-01-25 Online:2006-04-20 Published:2006-04-20
  • Supported by:
    Project supported by the National Natural Science Foundation of China (Grant No 20473038), the Foundation of High-Tech Project in Jiangsu province, China (Grant No BG-2005401).

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摘要： We have studied the transport property of the composites (La0.83Sr0.17 MnO3)1-x(ITO)x [ITO=(In2O3)0.95 (SnO2)0.05], which were fabricated by mechanically mixing La0.83Sr0.17 MnO3 and ITO grains. A giant positive magnetoresistance (PMR) has been observed above the Curie temperature Tc for samples with x around 0.40, in addition to the negative magnetoresistance related to spin-dependent interfacial tunnelling below Tc. For (La0.83Sr0.17MnO3)0.6(ITO)0.4, the magnetoresistive ratio for the PMR can reach 39.3% under a magnetic field H=2.24\tm105A/m. Theoretical analysis suggests that the magnetic-field-induced broadening of the p--n barrier between both kinds of grains and the density of the p--n heterostructures should be responsible for the PMR behaviour.

关键词: granular system, composite, giant magnetoresistance, p-n heterostructure

Abstract: We have studied the transport property of the composites (La0.83Sr0.17 MnO3)1-x(ITO)x [ITO=(In2O3)0.95 (SnO2)0.05], which were fabricated by mechanically mixing La0.83Sr0.17 MnO3 and ITO grains. A giant positive magnetoresistance (PMR) has been observed above the Curie temperature Tc for samples with x around 0.40, in addition to the negative magnetoresistance related to spin-dependent interfacial tunnelling below Tc. For (La0.83Sr0.17MnO3)0.6(ITO)0.4, the magnetoresistive ratio for the PMR can reach 39.3% under a magnetic field  $H=2.24\times10^5$ A/m. Theoretical analysis suggests that the magnetic-field-induced broadening of the p--n barrier between both kinds of grains and the density of the p--n heterostructures should be responsible for the PMR behaviour.

Key words: granular system, composite, giant magnetoresistance, p-n heterostructure

中图分类号:  (Giant magnetoresistance)

  • 75.47.De
61.05.cp (X-ray diffraction) 61.66.Fn (Inorganic compounds) 72.20.My (Galvanomagnetic and other magnetotransport effects) 72.80.Tm (Composite materials) 75.30.Kz (Magnetic phase boundaries (including classical and quantum magnetic transitions, metamagnetism, etc.))