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Oxygen vacancy and Mn2+induced ferromagnetism in Mn-doped ZnO thin films

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Science China(Technological Sciences) 2019年第10期62卷 1755-1759页

作者： GUAN SuJun NASU Naho ZHANG Yu TAMAMOTO Yuri YAMANOBE Maria ZHAO XinWei Department of Physics Tokyo University of ScienceTokyo162-8601Japan Department of Robotics The Open University of GuangdongGuangzhou510091China Department of Materials Science and Engineering Xihua UniversityChengdu610039China

With the purpose of investigating the origin of ferromagnetism(FM), Mn-doped Zn O thin films had been fabricated by radio frequency(rf) magnetron sputtering and subsequent anneal process. The characterization of the Mn-doped Zn O thin films was conducted by X-ray diffraction(XRD), X-ray photoelectron spectroscopy(XPS), and superconducting quantum interference device(SQUID). With increasing the anneal temperature from 300°C to 700°C for 3 min, the influence on magnetism of the Mndoped ZnO thin films is slight. While extending the anneal time from 3 to 50 min at 300°C, the influence on magnetism is obvious and the Mn-doped ZnO thin films with 30 min clearly demonstrate FM. Compared with the effect of oxygen vacancy and substitutional Mn2+on the ferromagnetic behavior, OVplays the main role in inducing FM of the Mn-doped ZnO thin films with good crystal structure.

关键词： oxygen vacancy Mn2+ ZnO thin films ferromagnetism

Observation of Room ferromagnetism in Cu-Implanted Crystal ZnO

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Chinese Physics Letters 2010年第8期27卷 211-213页

作者：李天晶李公平高行新陈景升 School of Nuclear Science and Technology Lanzhou University Lanzhou 730000 Department of Material Science and Engineering Nation'al University Singapore Singapore 119260 Singapore

Ion implantation technique is used to study the magnetic properties of Cu-dopecl ZnO. The room temperature ferromagnetism in the Cu-implanted ZnO samples is observed. From the photoluminescence spectrum of implanted samples we observe a broad green emission around 510nm, which is related to defects in the samples. X-ray photoelectron spectroscopy measurement shows that Cu ions are in the mixed oxidation state of 4-1 or ＋2 and substitute for the Zn^2＋ ions of the ZnO matrix. We argue that the ferromagnetism is related to these defects, and the substitution of Cu^2＋ into Zn^2＋ sites in crystal ZnO could contribute to the observed ferromagnetism.

关键词： OBSERVATION (Scientific method) ferromagnetism ZINC oxide COPPER ions ION implantation X-ray photoelectron spectroscopy PHOTOLUMINESCENCE

Room Temperature ferromagnetism and Structure of Zn_(1-x)Cu_xO Films Synthesized by Radio Frequency Magnetron Sputtering

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Plasma Science and Technology 2009年第5期11卷 582-586页

作者：陈学梅诸葛兰剑吴雪梅吴兆丰 School of Physical Science and Technology Soochow University Jiangsu Key Laboratory of Thin Films Soochow University Jiangsu Key Laboratory of Thin Films Soocbow University Analysis and Testing Center Sooehow University

Zn1-xCuxO thin films were synthesized by the radio frequency （RF） magnetron sputtering technique using a ZnO target containing different pieces of small Cu-chips. X-ray diffraction （XRD） and scanning electron microscopy （SEM） were employed to analyze the crystalline and microstructure of the film, and X-ray photoelectron spectroscopy （XPS） was used to establish the bonding characteristics and oxidation states of copper inside the ZnO host. Room temperature （RT） ferromagnetism was observed in the Znl-xCuxO films by a Quantum Design superconducting quantum interference device （SQUID） and the saturation magnetic moment of the films was found to decrease with the increase in Cu content.

关键词： RF magnetron sputtering Zn1-xCuxO film ferromagnetism

Acetic Acid Assistant Hydrogenation of Graphene Sheets with ferromagnetism

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Chemical Research in Chinese Universities 2018年第3期34卷 344-349页

作者： SUN Qiushi WANG Xiaofeng LI Benxian WU Yunpeng ZHANG Ziqing ZHANG Xinyang ZHAO Xudong LIU Xiaoyang State Key Laboratory of Inorganic Synthesis and Preparative Chemistry College of Chemistry Jilin University Changchun 130012 R R. China

ferromagnetism of pure carbon-based materials has been widely researched for several years. In therocially and experimentally, semi-hydrogenation graphene sheets exhibit ferromagnitism, which is related to the degree of hydrogenation. Here we reported the controllable hydrogenation of graphene using ball-milling method with acetic acid as hydrogenating agent. The hydrogenation graphene sheets were characterized by means of transmission electron microscopy（TEM）, Raman spectroscopy and X-ray photoelectron spectroscopy, and magnetic measurement. The relusts of Raman spectroscopy demonstrate that the relative intensity of D band increases with the hydrogenation degree. The resluts of magnetic meansurement indicate the maximal magnetic moment of 0.274 A·m^2/kg at 2 K for semi-hydrogenation graphene.

关键词： Graphene Hydrogenated graphene Ball-milling ferromagnetism

Effect of vanadium on the room temperature ferromagnetism of V-doped 6H-SiC powder

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Chinese Physics B 2013年第2期22卷 474-476页

作者：王辉严成锋孔海宽陈建军忻隽施尔畏 Shanghai Institute of Ceramics Chinese Academy of Sciences University of the Chinese Academy of Sciences

This study focuses on the effect of V-doping on the ferromagnetism（FM） of 6H-SiC *** X-ray diffraction results indicate that V is inserted into the 6H-SiC *** Raman spectra reveal that with a V concentration of 25 ppm,the crystalline quality and carrier concentration of 6H-SiC are hardly *** is found that after the V-doping process,the saturation magnetization（Ms） and the vacancy concentration of 6H-SiC are both *** these results,it is deduced that the effect of V might contribute mainly to the increase of vacancy concentration,thus resulting in the increase of Ms of V-doped 6H-SiC.

关键词： 6H-SiC V-doping ferromagnetism vacancy concentration

High-temperature ferromagnetism and strongπ-conjugation feature in two-dimensional manganese tetranitride

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Chinese Physics B 2023年第3期32卷 436-440页

作者：闫明谢志远高淼 Department of Mechanical and Aerospace Engineering Syracuse UniversitySyracuse 13244USA Department of Physics Renmin University of ChinaBeijing 100872China Department of Physics School of Physical Science and TechnologyNingbo UniversityNingbo 315211China

Two-dimensional(2D)magnetic materials have attracted tremendous research interest because of the promising application in the next-generation microelectronic ***,by the first-principles calculations,we propose a twodimensional ferromagnetic material with high Curie temperature,manganese tetranitride MnN4monolayer,which is a square-planar lattice made up of only one layer of *** structure is demonstrated to be stable by the phonon spectra and the molecular dynamic simulations,and the stability is ascribed to theπ–d conjugation betweenπorbital of N=N bond and d orbital of *** interestingly,the MnN_(4)monolayer displays robust 2D ferromagnetism,which originates from the strong exchange couplings between Mn atoms due to theπ–d *** high critical temperature of 247 K is determined by solving the Heisenberg model using the Monte Carlo method.

关键词： electronic structure first-priciples calculations two-dimensional materials ferromagnetism

Defect types and room-temperature ferromagnetism in undoped rutile TiO_2 single crystals

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Chinese Physics B 2013年第3期22卷 491-494页

作者：李东翔秦秀波郑黎荣李玉晓曹兴忠李卓昕杨静王宝义 Key Laboratory of Nuclear Analysis Techniques Institute of High Energy PhysicsChinese Academy of Sciences School of Physical Engineering Zhengzhou University Research Center for Application of Nuclear Technology Institute of High Energy PhysicsChinese Academy of Sciences Beijing Synchrotron Radiation Facility Institute of High Energy PhysicsChinese Academy of Sciences

Room-temperature ferromagnetism has been experimentally observed in annealed rutile TiO2 single crystals when a magnetic field is applied parallel to the sample *** combining X-ray absorption near the edge structure spectrum and positron annihilation lifetime spectroscopy,Ti^3＋-V O defect complexes（or clusters） have been identified in annealed crystals at a high *** elucidate that the unpaired 3d electrons in Ti^3＋ ions provide the observed room-temperature *** addition,excess oxygen ions in the TiO2 lattice could induce a number of Ti vacancies which obviously increase magnetic moments.

关键词： annealing oxygen vacancies Ti^3+-V O defect complexes ferromagnetism

Exotic ferromagnetism in the two-dimensional quantum material C3N

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Frontiers of physics 2018年第2期13卷 139-144页

作者： Wen-Cheng Huang Wei Li Xiaosong Liu State Key Laboratory of Functional Materials for Informatics Shanghai Institute of Microsystem and Information Technology Chinese Academy of Sciences Shanghai 200050 China CAS Center for Excellence in Superconducting Electronics Shanghai 200050 China School of Physical Science and Technology Shanghai Tech University Shanghai 201210 China

The search for and study of exotic quantum states in novel low-dimensional quantum materials have triggered extensive research in recent years. Here, we systematically study the electronic and magnetic structures in the newly discovered two-dimensional quantum material C3N within the framework of density functional theory. The calculations demonstrate that C3N is an indirect-band semiconductor with an energy gap of 0.38 eV, which is in good agreement with experimental observations. Inter- estingly, we find van Hove singularities located at energies near the Fermi level, which is half that of graphene. Thus, the Fermi energy easily approaches that of the singularities, driving the system to ferromagnetism, under charge carrier injection, such as electric field gating or hydrogen doping. These findings not only demonstrate that the emergence of magnetism stems from the itinerant electron mechanism rather than the effects of local magnetic impurities, but also open a new avenue to de- signing field-effect transistor devices for possible realization of an insulator-ferromagnet transition by tuning an external electric field.

关键词： quantum material ferromagnetism

Defect-manipulated magnetoresistance and above-room-temperature ferromagnetism in two-dimensional BaNi_(2)V_(2)O_(8)

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Chinese Chemical Letters 2024年第3期35卷 523-527页

作者： Pengfei Tan Chuanhui Zhu Jinjin Yang Shuang Zhao Tao Xia Mei-Huan Zhao Tao Han Zheng Deng Man-Rong Li Key Laboratory of Bioinorganic and Synthetic Chemistry of Ministry of Education School of ChemistrySun Yat-sen UniversityGuangzhou 510006China School of Science and Engineering The Chinese University of Hong KongShenzhen 518172China Institute of Physics Chinese Academy of SciencesBeijing 100190China School of Science Hainan UniversityHaikou 570228China

The intricate correlation between multiple degrees of freedom and physical properties is a fascinating area in solid state chemistry and condensed matter ***,we report a quantum-magnetic system BaNi_(2)V_(2)O_(8)(BNVO),in which the spin correlation was modulated by unusual oxidation state,leading to different magnetic *** BNVO was modified with topochemical reduction(TR)to yield TR-BNVO with partially reduced valance state of Ni^(+)in the two-dimensional NiO_(6)-honeycomb ***,the antiferromagnetic order is suppressed by the introduction of locally interposed Ni^(+)and oxygen vacancies,resulting in a ferromagnetic ground state with the transition temperature up to 710 K.A positive magnetoresistance(7.5%)was observed in the TR-BNVO at 40 K under 7 *** findings show that topological reduction is a powerful approach to engineer low-dimensional materials and accelerate the discovery of new quantum magnetism.

关键词： Layered honeycomb oxide Topochemical reduction Oxygen vacancies ferromagnetism Magnetoresistance