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Magnetism and Its Dependence on Annealing Temperature for Sputtered Co/Cu Multilayers

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Journal of Materials Science & Technology 1998年第2期14卷 139-142页

作者： Gao, Ruwei Liu, Yihua yan, shishen Zhang, Deheng Zhang, Lin Dept. of Physics Shandong University Jinan 250100 China

It was found that the easy magnetization axes of the films are parallel to the substrate, and the magnetic properties of both as-sputtered and annealed multilayers are isotropic in the film plane. The coercive field H//c is 4.8 kA/m and the ratio of remanence-to-saturation magnetization M//r/M//s is about 0.73 for as-sputtered samples. Both H//c and M//r/M//s increase with increasing annealing temperatures, especially when annealing temperatures are higher than 400 degree C. These experimental results can be interpreted by using the ferromagnetic exchange coupling and the pinning theory of the coercivity. (Edited author abstract) 13 Refs.

关键词： Cobalt alloys

Current spin polarization and spin injection efficiency in ZnO-based ferromagnetic semiconductor junctions

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Acta Metallurgica Sinica(English Letters) 2009年第2期22卷 153-160页

作者： Gang JI Ze ZHANG yanxue CHEN shishen yan Yihua LIU Liangmo MEI Institute of Microstructure and Properties of Advanced Materials Beijing University of Technology Beijing 100124 China Institute of Biophysics Chinese Academy of Sciences Beijing 100101 China School of Physics and National Key Laboratory of Crystal Materials Shandong University Jinan 250100 China

[FeNi（3 nm）/Zn1-xCoxO（3 nm）]2/ZnO（d nm）/[Zn1-xCoxO（3 nm）/Co（3 nm）]2 （d=3 and 10） semiconductor junctions were prepared by magnetron sputtering system and photolithography. The spin valve effect was observed in these junctions because the utility of the ferromagnetic composite layers acted as soft and hard magnetic layers. The electrical detection was performed by measuring the magnetoresistance of these junctions to investigate the current spin polarization asc in the ZnO layer and the spin injection efficiency η of spin-polarized electrons. asc was reduced from 11.7% （and 10.5%） at 90 K to 7.31% （and 5.93%） at room temperature for d=3 （and d=10）. And η was reduced from 39.5% （and 35.5%） at 90 K to 24.7% （and 20.0%） at room temperature for d=3 （and d=10）.

关键词： Spin injection Electrical detection Magnetoresistance Room temperature ferromagnetic semiconductor Ferromagnetic composite layers

Duplex Interpenetrating-Phase FeNiZn and FeNi_(3)Heterostructure with Low-Gibbs Free Energy Interface Coupling for Highly Efficient Overall Water Splitting

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Nano-Micro Letters 2023年第7期15卷 72-89页

作者： Qiuxia Zhou Caixia Xu Jiagang Hou Wenqing Ma Tianzhen Jian shishen yan Hong Liu Institute for Advanced Interdisciplinary Research(iAIR) Spintronics InstituteCollaborative Innovation Center of Technology and Equipment for Biological Diagnosis and Therapy in Universities of ShandongSchool of Chemistry and Chemical EngineeringUniversity of JinanJinan 250022People’s Republic of China School of Medical Information and Engineering Southwest Medical UniversityLuzhou 646000People’s Republic of China Kyiv College at Qilu University of Technology Qilu University of TechnologyShandong Academy of SciencesJinan 250353People’s Republic of China State Key Laboratory of Crystal Materials Shandong UniversityJinan 250100People’s Republic of China

The sluggish kinetics of both hydrogen evolution reaction(HER)and oxygen evolution reaction(OER)generate the large overpotential in water electrolysis and thus high-cost hydrogen ***,multidimensional nanoporous interpenetrating-phase FeNiZn alloy and FeNi_(3)intermetallic heterostructure is in situ constructed on NiFe foam(FeNiZn/FeNi_(3)@NiFe)by dealloying *** with the eminent synergism among specific constituents and the highly efficient mass transport from integrated porous backbone,FeNiZn/FeNi_(3)@NiFe depicts exceptional bifunctional activities for water splitting with extremely low overpotentials toward OER and HER(η_(1000)=367/245 mV)as well as the robust durability during the 400 h testing in alkaline *** as-built water electrolyzer with FeNiZn/FeNi_(3)@NiFe as both anode and cathode exhibits record-high performances for sustainable hydrogen output in terms of much lower cell voltage of 1.759 and 1.919 V to deliver the current density of 500 and 1000 mA cm^(-2)as well long working *** functional theory calculations disclose that the interface interaction between FeNiZn alloy and FeNi_(3)intermetallic generates the modulated electron structure state and optimized intermediate chemisorption,thus diminishing the energy barriers for hydrogen production in water *** the merits of fine performances,scalable fabrication,and low cost,FeNiZn/FeNi_(3)@NiFe holds prospective application potential as the bifunctional electrocatalyst for water splitting.

关键词： Heterostructure Interface effect Dealloying Bifunctional electrocatalyst Overall water splitting

Two-dimensional rectangular bismuth bilayer:A novel dual topological insulator

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Frontiers of physics 2023年第4期18卷 239-247页

作者： Shengshi Li Weixiao Ji Jianping Zhang Yaping Wang Changwen Zhang shishen yan Spintronics Institute School of Physics and TechnologyUniversity of JinanJinan 250022China State Key Lab of Crystal Materials and Institute of Crystal Materials Shandong UniversityJinan 250100China

Dual topological insulator(DTI),which simultaneously hosts topological insulator(TI)and topological crystalline insulator(TCI)phases,has attracted extensive attention since it has a better robustness of topological nature and broad application prospects in ***,the realization of DTI phase in two-dimensional(2D)system is extremely *** first-principles calculations,we predict that the 2D rectangular bismuth(R–Bi)bilayer is a novel DTI,featured by topological invariant=1,mirror Chern number C_(M)=–1,and metallic edge states within the bulk band *** interestingly,the TCI phase in bilayer is protected by horizontal glide mirror symmetries,rather than the usual mirror *** bulk band gap can be effectively tuned by vertical electric field and ***,the electric field can trigger the transition between TI and metallic phases for the bilayer,accompanied by the annihilation of TCI *** this basis,a topological field effect transistor is proposed,which can rapidly manipulate spin and charge carriers via electric *** KBr(110)surface is demonstrated as an ideal substrate for the deposition of *** findings provide not only a new strategy for exploiting 2D DTI,but also a promising candidate for spintronic applications.

关键词： dual topological insulator Bi bilayer glide mirror symmetry first-principles calculations

Spin Injection from Ferromagnetic Semiconductor CoZnO into ZnO

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Journal of Materials Science & Technology 2008年第3期24卷 415-418页

作者： Gang JI shishen yan yanxue CHEN Qiang CAO Wei XIA Yihua LIU Institute of Microstructure and Properties of Advanced Materials Beijing University of Technology Beijing 100124 China School of Physics and Microelectronics and National Key Laboratory of Crystal Materials Shandong University Jinan 250100 China School of Information Science and Engineering and National Key Laboratory of Crystal Materials Shandong University Jinan 250100 China

2x （FeNi/CoZnO）/ZnO/（CoZnO/Co） x2 spin-inJection devices were prepared by sputtering and photo-lithography. In the devices, two composite magnetic layers 2x（FeNi/CoZnO） and （CoZnO/Co）x2 with different coercivities were used to fabricate the ZnO-based semiconductor spin valve. Since the CoZnO ferromagnetic semiconductor layers touched the ZnO space layer directly, the significant spin injection from CoZnO into ZnO was observed by measuring the magnetoresistance of the spin-injection devices. The magnetoresistance reduced linearly with increasing temperature, from 1.12% at 90 K to 0.35% at room temperature.

关键词： Spin injection Magnetoresistance Ferromagnetic semiconductor

Gilbert damping in the layered antiferromagnet CrCl_(3)

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Chinese Physics B 2022年第2期31卷 581-586页

作者： Xinlin Mi Ledong Wang Qi Zhang Yitong Sun Yufeng Tian shishen yan Lihui Bai School of Physics State Key Laboratory of Crystal MaterialsShandong UniversityJinan 250100China

We theoretically and experimentally studied the Gilbert damping evolution of both acoustic and optical magnetic resonance modes in the layered flake Cr Cl;with an external magnetic field H applied in *** on a Lagrangian equation and a Rayleigh dissipation function,we predicted that the resonance linewidth△H as a function of microwave frequencyωis nonlinear for both acoustic and optical modes in the Cr Cl;flake,which is significantly different from the linear relationship of△H-ωin *** the microwave transmission through the Cr Cl;flake,we obtained theω–H dispersion and damping evolution△H–ωfor both acoustic and optical *** both our theoretical prediction and experimental observations,we concluded that the nonlinear damping evolution△H–ωis a consequence of the interlayer interaction during the antiferromagnetic resonance,and the interlayer Gilbert dissipation plays an important role in the nonlinear damping evolution because of the asymmetry of the non-collinear magnetizaiton between layers.

关键词： Gilbert damping antiferromagnetic resonance(AFMR) CrCl_(3)

The predicaments and expectations in development of magnetic semiconductors

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Journal of Semiconductors 2019年第8期40卷 9-19页

作者： Qiang Cao shishen yan Spintronics Institute University of Jinan

Over the past half a century, considerable research activities have been directing towards the development of magnetic semiconductors that can work at room temperature. These efforts were aimed at seeking room temperature magnetic semiconductors with strong and controllable s, p-d exchange interaction. With this s, p-d exchange interaction, one can utilize the spin degree of freedom to design applicable spintronics devices with very attractive functions that are not available in conventional semiconductors. Here, we first review the progress in understanding of this particular material and the dilemma to prepare a room temperature magnetic semiconductor. Then we discuss recent experimental progresses to pursue strong s, p-d interaction to realize room temperature magnetic semiconductors, which are achieved by introducing a very high concentration of magnetic atoms by means of low-temperature nonequilibrium growth.

关键词： magnetic semiconductors s, p-d interaction high concentration of magnetic atoms low temperature nonequilibrium growth semiconductor spintronics

Magnetic coupling governed pinning directions in magnetic tunnel junctions under magnetic field annealing with zero magnetic field cooling

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Science China(Information Sciences) 2023年第4期66卷 305-306页

作者： Weibin CHEN Shaohua yan Zhiqiang CAO Shiyang LU Xiaonan ZHAO Runrun HAO Zitong ZHOU Zhi LI Kun ZHANG shishen yan Qunwen LENG School of Physics State Key Laboratory of Crystal Materials Shandong University Fert Beijing Institute MIIT Key Laboratory of Spintronics School of Integrated Circuit Science and Engineering Beihang University

With the rapid development of emerging concepts, such as the Internet of things and big data, the use of various magnetoresistance(MR) sensors, especially tunneling MR(TMR) in magnetic tunnel junctions(MTJs), for information perception is considered the critical first step. A typical topic in this field is the construction of a Wheatstone bridge structure to restrain the temperature drift and amplify the magnetic response signal.

关键词： Magnetic fields

Janus VXY monolayers with tunable large Berry curvature

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Journal of Semiconductors 2022年第4期43卷 96-111页

作者： Wenrong Liu Xinyang Li Changwen Zhang shishen yan School of Physics and Technology Spintronics InstituteUniversity of JinanJinan 250022China

The Rashba effect and valley polarization provide a novel paradigm in quantum information technology. However,practical materials are scarce. Here, we found a new class of Janus monolayers VXY(X = Cl, Br, I;Y = Se, Te) with excellent valley polarization effect. In particular, Janus VBrSe shows Zeeman type spin splitting of 14 meV, large Berry curvature of 182.73 bohr2,and, at the same time, a large Rashba parameter of 176.89 meV·?. We use the k·p theory to analyze the relationship between the lattice constant and the curvature of the Berry. The Berry curvature can be adjusted by changing the lattice parameter,which will greatly improve the transverse velocities of carriers and promote the efficiency of the valley Hall device. By applying biaxial strain onto VBrSe, we can see that there is a correlation between Berry curvature and lattice constant, which further validates the above theory. All these results provide tantalizing opportunities for efficient spintronics and valleytronics.

关键词： Janus VXY valley polarization k·p theory large Berry curvature