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MAGNETIC PROPERTIES AND colossal MAGNETORESISTANCE OF La_1-xSr_xMn_0.88Fe_0.12O₃

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中国有色金属学会会刊：英文版 1998年第4期8卷 101-104页

作者： Xianyu Wenxu, Li Baohe , Qian Zhengnan, Li Tian, Wang Xiangqun and Zhao Tiesong Department of Physics, Jilin University, Changchun 130023, P.R.China Light industrial College, Beijing 100037, P. R. China

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关键词： LaSrMnFeO compound magnetic properties colossal magnetoresistance sol gel technique

Origin of colossal Magnetoresistance in Nd1-xCaxMnO3

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电子显微学报 1997年第4期 69-70页

作者： K.Liu\ X.W.Wu\ K.H.Ahn\ C.L.Chien (Dept. of Physics and Astronomy, The Johns Hopkins University, Baltimore, MD 21218) John Q.Xiao (Dept. of Physics and Astronomy, University of Delaware, Newark, DE 19716)

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关键词： Nd Ca Origin colossal Magnetoresistance x)CaxMnO3

Anomalous magnetotransport in LaMn_(1-x)Te_xO_3

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Science China(Physics,Mechanics & Astronomy) 2009年第7期52卷 987-992页

作者： TAN GuoTai1,2, CHEN ZhengHao3 & ZHANG XiaoZhong4,5 1 Key Laboratory of Beam Technology & Materials Modification of the Ministry of Education, Institute of Low Energy Nuclear Physics, Beijing Normal University, Beijing 100875, China 2 Beijing Radiation Center, Beijing 100875, China 3 Laboratory of Optical Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100080, China 4 Key Laboratory of Advanced Materials of the Ministry of Education, Department of Materials Science and Engineering, Tsinghua University, Beijing 100084, China 5 Beijing National Center for Electron Microscopy, Tsinghua University, Beijing 100084, China Key Laboratory of Beam Technology & Materials Modification of the Ministry of Education Institute of Low Energy Nuclear Physics Beijing Normal University Beijing China Beijing Radiation Center Beijing China Laboratory of Optical Physics Institute of Physics Chinese Academy of Sciences Beijing China Key Laboratory of Advanced Materials of the Ministry of Education Department of Materials Science and Engineering Tsinghua University Beijing China Beijing National Center for Electron Microscopy Tsinghua University Beijing China

The LaMn1-xTexO3+δ (x=0.1, 0.2, 0.3) were synthesized using solid-state reaction method for the first time. X-ray photoemission spectrum (XPS) shows that in the samples the Te ions have a valence of Te4+, and Mn3+ ions are partly converted into Mn2+ and Mn4+ due to the excess oxygen and Te doping. The magnetotransport associated with Mn2+, Mn3+ and Mn4+ was investigated. The experimental results show that the samples are insulator at 0 T when the amount of Mn3+ is much larger or less than the sum of Mn2+ and Mn4+; by contrast, the samples display metal to insulator transition with increasing temperature when the amount of Mn3+ is close to the sum of Mn2+ and Mn4+. These anomalous magnetotransport behaviors were analyzed in the frame of the double-exchange (DE) mechanism.

关键词： colossal magnetoresistance La-Te-Mn-O magnetotransport

Field dependence of magnetoresistance in epitaxial single-crystal La_(2/3)Ca_(1/3)MnO_(3-δ) thin film

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Science China Mathematics 1999年第1期42卷 99-105页

作者：李可斌程荣胜王守国陈志祥方军王智河曹效文许小军朱警生张裕恒 Institute of Solid State Physics Chinese Academy of Sciences Hefei China High Magnetic Field Laboratory Institute of Plasma Physics Chinese Academy of Sciences Hefei China Structural Research Laboratory University of Science and Technology of China Hefei China

Epitaxial La2/3Ca1/3MnO3 thin films were prepared on NdGaO3 （110） substrates by d.c. magnetron sputtering method. The measurements of magnetoresistance ρ（H） upon magnetic field at different temperatures were carried out in the field range of 0—8 T. It is found that ρ（H） obeys the following relations: when the temperature （T） is higher than the Curie temperature TC, ρ（H）=1/（α（T）+β（T）H2）; below TC, ρ（H）=ρ0（T）+1/(A（T）+B（T）exp（H/c（T））, and ρ（H）=（1/（σ（T）+γ（T）H）） when T is far below TC. It is suggested that the negative magnetoresistive effect is mainly due to enhancement of the magnetoconductanee.

关键词： epitaxial La2/3Ca1/3Mno3 thin films colossal magnetoresistive effect field dependence of magnetore-sistance.

Effect of A-site cation substitution on magnetic transition temperature of (LaCa) MnO_3

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Science China Mathematics 1999年第7期42卷 758-762页

作者：李可斌王守国程荣胜李西军侯登录聂向富张裕恒 Institute of Solid State Physics Chinese Academy of Sciences Hefei China Structural Research Laboratory University of Science and Technology of China Hefei China Department of Physics Hebei Teacher’s College Shijiazhuang China

The ferromagnetic transition temperatures have been measured on two bathes of perovskite manganese oxides such as (La1-xRx)2/3Ca1/3MnO3（R=Ce, Pr, Nd, etc.） and La2/3(Ca1-yCd)y)1/3MnO3. It is found that the (La1-xRx)2/3Ca1/3MnO3 samples have obviously different Curie temperature TC although their A> （the average A-site cation radius） are almost identical, and the TC in the system of (La1-xRx)2/3Ca1/3MnO3 compounds increases with increasing y although A> decreases slightly. It is suggested that the Curie temperature should be influenced by the average local A-site magnetic moment in the ferromagnetic perovskite manganite system.

关键词： colossal magnetoresistance Curie temperature ( Tc) lattice effect.

Cu doping effect on Mn sites of La_(2/3)Ca_(1/3) MnO_3 system

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Chinese Science Bulletin 1998年第17期43卷 1442-1447页

作者： SUN Xia, TANG Ping, CHEN Yue, HUANG Zhen, LI Guang,LIU Zhimin, CHEN Zhiyou, WANG Sheng and YUAN Songliu High Magnetic Field Laboratory, Institute of Plasma Physics, Chinese Academy of Sciences, P. O. Box 1126, Hefei 230031, China High Magnetic Field Laboratory Institute of Plasma Physics Chinese Academy of Sciences Hefei China

The temperature dependence of resistance and magnetoresistance at 77 K for Cu-doped La 2/3Ca 1/3Mn 1-xCu xO-3 have been investigated. Besides the transition similar to the Cu-free sample at ～260 K, a new transition at lower temperature appears for Cu-doped samples. The new transition moves toward low temperature with increasing of Cu content. A new conductive proceeding related to Cu ion may exist. Magnetoresistance at liquid nitrogen shows that MR increased three orders when x is changed from 0 to 0 15. Moreover, the main variation of magnetoresistance is below the field of 1 T.

关键词： colossal magnetoresistance Cu doping transfer behavior charge transfer.

Structural, magnetic and transport properties of Sc-doped La0.7Sr0.3MnO_3

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Chinese Science Bulletin 2000年第9期45卷 810-814页

作者： YAN Chunhua, HUANG Yunhui, WANG Zheming, ZHANG Lei, GAO Song, LIAO Chunsheng & XU GuangxianState Key Laboratory of Rare Earth Materials Chemistry and Applications, PKU-HKU Joint Laboratory in Rare Earth Materials and Bioinorganic Chemistry, Peking University, Beijing 100871, China State Key Laboratory of Rare Earth Materials Chemistry and Applications PKU-HKU Joint Laboratory in Rare Earth Materials and Bioinorganic Chemistry Peking University Beijing China

The Sc-doped La0.7Sr0.3MnO3 polycrystallines were prepared by thermal decomposition of complexes of metal ions with ethylenediamine-tetraacetic acid (EDTA). The dependence of structural, magnetic and transport properties on Sc doping was investigated. Moderate Sc doping level results in a sharp drop in Curie temperature, an increase in resistance and enhancement of magnetoresistance effect. At temperatures above TMI, R(T) can be described as R(T) = R0exp(T0/T)1/4, which indicates that conduction takes place by hopping between the localized states. The experimental data reveal that the change in magnetoresistance property is related to the structure.

关键词： scandium perovskite colossal magnetoresistance thermal decomposition.

Spatial confinement tuning of quenched disorder effects and enhanced magnetoresistance in manganite nanowires

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Science China(Physics,Mechanics & Astronomy) 2020年第3期63卷 106-111页

作者： Yang Yu Qiang Li Qian Shi YinYan Zhu HanXuan Lin Hao Liu HongYan Chen Tian Miao Yu Bai YanMei Wang WenTing Yang WenBin Wang HangWen Guo LiFeng Yin Jian Shen State Key Laboratory of Surface Physics and Department of Physics Fudan UniversityShanghai 200433China Institute for Nanoelectronic Devices and Quantum Computing Fudan UniversityShanghai 200433China Collaborative Innovation Center of Advanced Microstructures Nanjing 210093China

Complex oxides have rich functionalities and advantages for future *** many systems,quenched disorder often holds the key to determine their physical properties,and these properties can be further tuned by chemical ***,understanding the role of quenched disorder is complicated because chemical doping simultaneously alters other physical variables such as local lattice distortions and electronic and magnetic ***,we show that spatial confinement is an effective approach to tuning the level of quenched disorder in a complex-oxide system while leaving other physical variables largely *** the confinement of a manganite system down to quasi-one-dimensional nanowires,we observed that the nature of its metal-insulator phase transition exhibits a crossover from a discontinuous to a continuous characteristic,in close accordance with quenched disorder *** argue that the quenched disorder,finite size,and surface effects all contribute to our experimental ***,with reduced nanowire width,the magnetoresistance shows substantial enhancement at low *** findings offer new insight into experimentally tuning the quenched disorder effect to achieve novel functionalities at reduced dimensions.

关键词： quenched disorder manganite nanowires phase transition colossal magnetoresistance

Thoughts of a travelling ecologist *** fighting exotics ever succeed?

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生物安全学报 2016年第2期25卷 75-76页

作者： Gbor L.LVEI Institute of Applied Ecology Fujian Agriculture and Forestry University Department of Agroecology Aarhus UniversityFlakkebjerg Research Centre

We live in the Age of Extinctions-the call for naming our time＂Anthropocene＂is no more than hubris and escapism from this colossal *** the6thmass extinction has possibly already started（Barnosky et al.,2011）,and it may prove the largest so far to be endured by life on Earth,efforts are needed not to turn this into the Age of Loneliness,when humans may find themselves Masters of the Earthbut alone（Wilson,2014）.

关键词： extinction fighting colossal themselves alone possibly travelling succeed reasons argue