Co替代Mn对Pr_(0.6)Ca_(0.4)MnO_3磁性质及电荷有序的影响  

Magnetic Properties and Charge Ordering of Pr_(0.6)Ca_(0.4)MnO_3 with Co Substitution for Mn

作　　者：胡学青[1,2] 王桂英[1,2] 刘鹏[1,2] 罗鹏[1,2] 李莉[1,2] 彭振生[1] 

机构地区：[1]宿州学院自旋电子与纳米材料安徽省重点实验室,安徽宿州234000 [2]宿州学院机械与电子工程学院,安徽宿州234000

出　　处：《稀有金属》2016年第6期574-580,共7页Chinese Journal of Rare Metals

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重点项目(KJ2013A245);安徽省优秀青年人才支持计划重点项目(GXYQZD2016341);宿州学院科研平台开放课题(2014YKF48)资助

摘　　要：用固相反应法制备Pr_(0.6)Ca_(0.4)Mn_(1-x)CoxO_3(x=0,0.02,0.04,0.06)系列多晶样品。通过X射线衍射(XRD)图谱检测样品的结构,通过零场冷(ZFC)和加场冷(FC)的磁化强度-温度(M-T)曲线,电子自旋共振(ESR)图谱,研究Co替代Mn对Pr_(0.6)Ca_(0.4)Mn O_3磁性质及电荷有序相的影响。结果表明:母体样品的宏观磁性质随温度的变化而发生多重变化,在238 K出现电荷有序相,TCO=238 K,200~173 K温区的ZFC曲线出现一个平台,173 K为Neel温度,即T_N=173 K,在40 K附近ZFC曲线出现一个尖峰,样品出现自旋玻璃态,自旋玻璃态转变温度T_f=40 K。Co替代Mn对Pr_(0.6)Ca_(0.4)Mn O_3的磁性质及电荷有序相影响明显,所有掺Co样品都没有表现出电荷有序特征,随温度降低从顺磁向铁磁/反铁磁混合相转变。Co替代Mn对电荷有序的破坏非常容易,当Co替代量x=0.02时电荷有序相被完全融化。Co替代Mn对电荷有序相的破坏之所以容易,是因为用非Jahn-Teller(JT)离子Co^(3+)替代JT离子Mn^(3+),削弱了Jahn-Teller畸变,间接证明Jahn-Teller电-声子相互作用是产生电荷有序的主要原因。Polycrystalline Pr0.6 Ca0.4 Mn1-x Cox O3 （ x = 0, 0.02, 0.04, 0.06 ） samples were prepared by solid-state reaction method. The structure of the samples was detected by X-ray diffraction （XRD） patterns, and the influences of Co substitution for Mn on mag- netic properties and charge ordering phase of Pr0.6 Ca0.4 MnO3 were studied through the measurements of zero-field-cooling （ZFC） and field-cooling （FC） magnetization-temperature （M-T） curves and electron spin resonance （ESR） spectra. The results indicated that the macro magnetic property of the original sample exhibited multiple changes with the change of temperature, charge ordering phase ap- peared at 238 K （Tco = 238 K）, the ZFC curve in the temperature range of 200 - 173 K exhibited a platform, then Neel temperature was 173 K, i.e. TN = 173 K, and the ZFC curve exhibited a sharp peak near 40 K, then the sample was in spin glass state, and the transition temperature of spin glass state was Tf = 40 K. The influences of Co substitution for Mn on magnetic properties and charge or- dering phase of Pr0.6Ca0.4MnO3 were apparent, all the samples with Co doping showed no charge ordering characteristic, and trans- formed from paramagnetism to ferromagnetic/anti-ferromagnetic mixed phase with the decrease of temperature. Co substitution for Mn destroyed charge ordering phase very easily, and the charge ordering phase was melted completely when the Co substitution amount was x =0.02. This was because Jahu-Teller （JT） ion Mn^3＋ was substituted by non-JT ion Co^3＋, then Jahn-Teller distortion weakened. This article indirectly proved that the Jahn-Teller electron-phonon interaction was the main reason of charge ordering appearance.

关 键 词：Co替代Mn 磁性质 电荷有序 JAHN-TELLER畸变 钙钛矿氧化物 

分 类 号：O482.54[一般工业技术—材料科学与工程] TM273[理学—固体物理]