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Improvement on Electrical Properties and Magnetoresistance Induced by Pd or Ag Addition in La0.67(Ca0.65Ba0.35)0.33MnO3 Manganites
Xiao-bo Yuan*,Jun-feng Ren
Author NameAffiliationE-mail
Xiao-bo Yuan* College of Physics and Electronics, Shandong Normal University, Ji'nan 250014, China yxb@sdnu.edu.cn 
Jun-feng Ren College of Physics and Electronics, Shandong Normal University, Ji'nan 250014, China  
Abstract:
Electrical properties and magnetoresistance have been studied in two series of xAg-La0.67(Ca0.65Ba0.35)0.33MnO3 and xPd-La0.67(Ca0.65Ba0.35)0.33MnO3 (abbreviated by xAg-LCBMO and xPd-LCBMO) composites. Both Pd and Ag addition induce a decrease in resistivity and an increase in temperature at which the resistivity reaches its maximum. This is mainly due to the improvement of grain boundaries caused by the segregation of good conductive metal grains on the grain boundaries/surfaces. In addition, both Pd and Ag addition induce a large enhancement of room temperature magnetoresistance (RTMR). Note that 27% molar ratio of Ag addition induces a large RTMR of about 70%, about ten times larger than pure LCBMO, whereas 27% molar ratio Pd addition brings a much larger RTMR of about 170%. The large enhancements of MR can be attributed to the decrease in resistivity of the samples caused by the good conductive metal. On the other hand, the polarization of Pd atoms near the Mn ions on the grain surfaces/boundaries plays a very im-portant role in the increase in MR, which induces a large number of spin clusters in Pd-added samples.
Key words:  Colossal magnetoresistance, Ag-added manganite, Pd-added manganite, Room temperature magnetoresistance, Spin cluster, Polarization of Pd atom
FundProject:
Pd/Ag掺杂的La0.67(Ca0.65Ba0.35)0.33MnO3体系电特性和磁电阻增强效应
原晓波*,任俊峰
摘要:
系统研究了xAg-La0.67(Ca0.65Ba0.35)0.33MnO3和xPd-La0.67(Ca0.65Ba0.35)0.33MnO3(xAg-LCBMO和xPd-LCBMO)两种复合体系的电特性和磁电阻特性. 结果发现,Pd和Ag的掺杂都引起电阻率的大幅降低和峰值电阻率温度的升高,这主要源于晶粒边界/表面良导体金属晶粒的析出. 另外,Pd和Ag的掺杂都引起室温磁电阻的大幅增强. 尤其是27%摩尔比的Ag掺杂诱导了高达70%的室温磁电阻,几乎是未掺杂母体LCBMO的10倍,而27%摩尔比的Pd掺杂诱导产生了更高的磁电阻,约170%. 磁电阻的大幅增强,与良导体金属掺杂引起的样品电阻率的降低有关. 另一方面,晶粒表面/边界Mn离子与Pd离子接近诱导Pd离子的自旋极化对磁电阻的增强起了重要的促进作用.
关键词:  庞磁电阻效应,Ag掺杂锰氧化物,Pd掺杂锰氧化物,室温磁电阻效应,自旋团簇,Pd原子的磁极化效应
DOI:10.1063/1674-0068/26/04/431-438
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