Magnetic and Magnetoresistance Properties in (La0.67 Ca0.33 MnO3)x/(ZrO2 )1-x Composite System
来源期刊：JOURNAL OF RARE EARTHS2005年第2期
论文作者：LIU Yihua Yuan Xiaobo Wang Chengjian HAO Xiaopeng HUANG Baoxin Zhang Ruzhen
Key words：inorganic non-metallic materials; composite system; colossal magnetoresistance; interfacial tunneling; low-field magnetoresistance; rare earths;
Abstract: (La0.67Ca0.33MnO3)x /(ZrO2)1-x (x is the volume fraction ratio) percolated composites were fabricated by combining La0.67Ca0.33MnO3 (LCMO) powders with ZrO2 particles, where LCMO powders were prepared by sol-gel process. Low field magnetoresistance ( LFMR ) is greatly enhanced at low temperature when the system is close to the metallic percolation threshold of x=0.4. The magnetoresistance ratio of ( LCMO)0.4 /( ZrO2 )0.6 in a 10 mT magnetic field at 77 K is 7.8 %, about 7.12 times larger than that of pure LCMO compound. The enhancement of spin-dependent tunneling of electrons at the interfaces between LCMO and ZrO2 grains is responsible for the enhanced LFMR. With increasing ZrO2 addition, Curie temperature TC decreases firstly and then remains constant at about 220 K when x<60%, showing limited substitution effect of Zr ions on B sites.
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Abstract:(La0.67Ca0.33MnO3)x /(ZrO2)1-x (x is the volume fraction ratio) percolated composites were fabricated by combining La0.67Ca0.33MnO3 (LCMO) powders with ZrO2 particles, where LCMO powders were prepared by sol-gel process. Low field magnetoresistance ( LFMR ) is greatly enhanced at low temperature when the system is close to the metallic percolation threshold of x=0.4. The magnetoresistance ratio of ( LCMO)0.4 /( ZrO2 )0.6 in a 10 mT magnetic field at 77 K is 7.8 %, about 7.12 times larger than that of pure LCMO compound. The enhancement of spin-dependent tunneling of electrons at the interfaces between LCMO and ZrO2 grains is responsible for the enhanced LFMR. With increasing ZrO2 addition, Curie temperature TC decreases firstly and then remains constant at about 220 K when x<60%, showing limited substitution effect of Zr ions on B sites.
Key words:inorganic non-metallic materials; composite system; colossal magnetoresistance; interfacial tunneling; low-field magnetoresistance; rare earths;
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