(La_(0．7)Sr_(0．3)MnO_3)_((1-x))(CoFe_2O_4)_x复合体中增强的室温磁电阻效应  

Enhanced room temperature magnetoresistance in (La_(0.7)Sr_(0.3)MnO_3)_((1-x))(CoFe_2O_4)_x composites

作　　者：席力[1] 田航[1] 刘杰[1] 葛世慧[1] 杨啸林[1] 李成贤[1] 

机构地区：[1]兰州大学磁学与磁性材料教育部重点实验室,甘肃兰州730000

出　　处：《兰州大学学报（自然科学版）》2008年第1期108-111,共4页Journal of Lanzhou University(Natural Sciences)

基　　金：国家自然科学基金(50371034;50701021)资助

摘　　要：利用溶胶—凝胶法制备了(La_(0.7)Sr_(0.3)MnO_3)_((1-x))(CoFe_2O_4)_x复合体材料,并利用X射线衍射和^(57)Fe的穆斯堡尔谱详细研究了其结构和微结构.利用超导量子磁强计测量了样品的磁性.结构和磁性的测量表明(La_(0.7)Sr_(0.3)MnO_3)_((1-x))(CoFe_2O_4)_x复合体由La_(0.7)Sr_(0.3)MnO_3和CoFe_2O_4组成,两相之间没有反应.复合体的电阻率随着CoFe_2O_4的加入而逐渐升高.在室温条件下5kOe的磁场下得到了-5%的磁电阻效应,该值比同样晶粒大小的纯La_(0.7)Sr_(0.3)MnO_3样品的磁电阻效应大一倍.同时也比将非磁性的绝缘势垒如玻璃、CeO_2等引入La_(0.7)Sr_(0.3)MnO_3的室温磁电阻值大.表明一定量的铁磁性绝缘势垒的引入可以增强类钙钛矿锰氧化物的室温磁电阻效应.（La0.7Sr0.3MnO3）（1-x）（eoFe2O4）x composites were fabricated by the sol-gel method. X-ray diffraction, MSssbaner spectroscopy, SQUID and resistivity measurements were used to investigate the struc- ture, microstructure, magnetic properties and magnetoresistance （RM） effect of the samples. The resistivity of （La0.7Sr0.3MnO3）（1-x）（CoFe2O4）x increases with the increase of x. The magnetoresistance （-5%） is about two times larger than that of the same-grain-sized La0.7Sr0.3MnO3 sample in the field of 5 kOe at roomtemperature. Our results indicate that the magnetoresistance effect can be enhanced by introducing ferromagnetic barrier in perovskite manganites.

关 键 词：类钙钛矿锰氧化物 隧道效应 磁电阻效应 

分 类 号：O484.4[理学—固体物理]