Cr替代Mn对La_(0.4)Ca_(0.6)MnO_3磁性质的影响  

Influence of the Substitution of Cr for Mn on Magnetic Properties of La_(0.4)Ca_(0.6)MnO_3

作　　者：王桂英[1,2] 杨刚[1,2] 郭焕银[1,2] 毛强[1,2] 叶吾梅[1,2] 彭振生[1,3] 

机构地区：[1]自旋电子与纳米材料安徽省重点实验室(培育基地),宿州234000 [2]宿州学院电子与电气工程系,宿州234000 [3]中国科学技术大学合肥微尺度物质科学国家实验室,合肥230026

出　　处：《无机材料学报》2011年第4期411-416,共6页Journal of Inorganic Materials

基　　金：国家自然科学基金重点项目(19934003);安徽省教育厅自然科学研究项目(KJ2008A19ZC;KJ2008A34ZC;KJ2009B281Z;KJ2010B228;KJ2010B229)~~

摘　　要：用固相反应法制备了La0.4Ca0.6Mn1-xCrxO3(x=0.00,0.02,0.04,0.06,0.08,0.10,0.15)多晶样品,通过X射线衍射(XRD)图谱、磁化强度-温度(M-T)曲线、电子自旋共振(ESR)谱线,研究了Cr替代Mn对La0.4Ca0.6MnO3磁性质的影响.实验结果表明:La0.4Ca0.6MnO3存在复杂的磁结构,在258 K出现电荷有序相,从175 K到50 K,产生强关联CO-AFM(电荷有序?反铁磁)相,温度降到41 K左右出现自旋玻璃态;当替代量x≥0.06时,电荷有序相被融化;当x≥0.10时,自旋玻璃态被融化.对实验结果进行了初步解释:电荷有序相被融化主要原因是Cr3+与Mn4+具有相同的电子结构,Cr3+替代Mn3+破坏了CE型反铁磁的自旋序,从而引起电荷序的坍塌,实验证明了电荷序CE型反铁磁体系中,电荷序和自旋序之间存在强耦合相互作用;自旋玻璃态的融化,是由于Cr替代Mn破坏了自旋玻璃态的生成条件,即反铁磁背景下有少量铁磁成分.Polycrystalline samples of La0.4Cao.6Mn1？xCrxO3（x=0.00,0.02,0.04,0.06,0.08,0.10,0.15）were prepared by the solid state reaction method.The influence of Cr3＋ substitution for Mn3＋ on the magnetic property and charge ordering phase of La0.4Ca0.6MnO3 was studied through the measurements of X-ray diffraction（XRD）,magnetization-temperature（M-T） curves and electron spin resonance（ESR） spectra.The experimental results indicate that the sample of La0.4Ca0.6MnO3 has very complicated magnetic structure.The charge ordering phase of the sample exhibits at 258K,and strong correlated CO-AFM phase shows from 175K to 50K.The spin glass state of the sample appears when the temperature decreases to about 41K.When the Cr substitution amount x is more than 0.06,the charge ordering phase of the sample is destroyed.When x is larger than 0.10,spin-glass state is melt.In addition,experimental results are explained preliminarily as follows： because Cr3＋ and Mn4＋ have the same electronic structure,Cr3＋ substitution for Mn3＋ destroys the spin order of CE-type antiferromagnetism,and thus leads to the destruction of charge ordering.It is verified experimentally that the strong coupling between charge ordering and spin ordering exists in the charge order system of CE-type anti-ferromagnetism,and Cr3＋ substitution for Mn3＋ destroys formation conditions of spin-glass state that small ferromagnetic component exists at the background of antiferromagnetism.

关 键 词：La0.4La0.6MnO3 CR掺杂 电荷有序 自旋玻璃 

分 类 号：O482[理学—固体物理] TM273[理学—物理]