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Modulation of magnetic properties and enhanced magnetoelectric effects in MnW_(1-x)Mo_xO_4 compounds

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Chinese Physics B 2014年第7期23卷 703-707页

作者：房勇周卫平宋育全吕丽娅王敦辉都有为 National laboratory of solid state Microstructures and Key laboratory of Nanomaterials for Jiangsu Province Nanjing University

In this letter, we investigate the magnetic and ferroelectric properties of polycrystalline MnW1-xMoxO4 （x = 0, 0.05, 0.10, 0.20） compounds. The substitution of nonmagnetic Mo6＋ ions for W6＋ ions modifies the magnetic transition tem- peratures of MnW1-xMoxO4 by changing the Mn-O-Mn bond. As a result, distinct ferroelectric properties and enhanced magnetoelectric effects are observed in Mo6＋-doped MnWO4 compounds. The effects of substitution of Mo6＋ ions on magnetic properties and magnetoelectric coupling are discussed.

关键词： magnetism ferroelectricity magnetoelectric effects multiferroic properties

Scaling dependence of memory windows and different carrier charging behaviors in Si nanocrystal nonvolatile memory devices

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Chinese Physics B 2016年第9期25卷 518-522页

作者：于杰陈坤基马忠元张鑫鑫江小帆吴仰晴黄信凡 Shunri Oda state Key laboratory of solid state Microstructures and School of Electronic Science and Engineering Nanjing University Quantum Nanoelectronics research Center Tokyo Institute of Technology

Based on the charge storage mode,it is important to investigate the scaling dependence of memory performance in silicon nanocrystal（Si-NC） nonvolatile memory（NVM） devices for its scaling down *** this work,we made eight kinds of test key cells with different gate widths and lengths by 0.13-μm node complementary metal oxide semiconductor（CMOS） *** is found that the memory windows of eight kinds of test key cells are almost the same of about1.64 V @ ±7 V/1 ms,which are independent of the gate area,but mainly determined by the average size（12 nm） and areal density（1.8×10^（11）/cm^2） of *** program/erase（P/E） speed characteristics are almost independent of gate widths and ***,the erase speed is faster than the program speed of test key cells,which is due to the different charging behaviors between electrons and holes during the operation ***,the data retention characteristic is also independent of the gate *** findings are useful for further scaling down of Si-NC NVM devices to improve the performance and on-chip integration.

关键词： silicon nanocrystals nonvolatile memory scaling dependence different charging behaviors

Effects of the Mn/Co ratio on the magnetic transition and magnetocaloric properties of Mn_(1+x)Co_(1-x)Ge alloys

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Chinese Physics B 2011年第8期20卷 411-414页

作者：马胜灿王敦辉轩海成沈凌佳曹庆琪都有为 National laboratory of solid state Microstructures and Key laboratory of Nanomaterials for Jiangsu Province Nanjing University

We have investigated the magnetic transition and magnetocaloric effects of Mn1＋xCo1-xGe alloys by tuning the ratio of Mn/Co. With increasing Mn content, a series of first-order magnetostructural transitions from ferromagnetic to paramagnetic states with large changes of magnetization are observed at room temperature. Further increasing the content of Mn （x = 0.11） gives rise to a single second-order magnetic transition. Interestingly, large low-field magnetic entropy changes with almost zero magnetic hysteresis are observed in these alloys. The effects of Mn/Co ratio on magnetic transition and magnetocaloric effects are discussed in this paper.

关键词： Mn/Co ratio magnetic transition magnetocaloric properties magnetic hysteresis losses

DEFORMATION OF COPOLYMER MICELLES INDUCED BY AMPHIPHILIC DIMER PARTICLES

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Chinese Journal of Polymer Science 2012年第2期30卷 164-172页

作者： Xiao-chun Qin Chun-lai Ren National laboratory of solid state Microstructures Nanjing UniversityNanjing 210093China

Combining self-consistent-field theory and density-functional theory, we systematically study the deformation of copolymer micelles induced by the presence of amphiphilic dimer particles. Due to the amphiphilic nature, dimer particles tend to accumulate onto the interface of the copolymer micelle. With increasing concentration of the symmetric dimer particles, which are made of two identical spherical particles, the micelle deforms from the initial sphere to ellipse, dumbbell, and finally separates into two micelles. Furthermore, asymmetric dimer particles, composed by two particles with different sizes, are considered to investigate the influence of geometry of dimer particles on the deformation of the micelle. It is found that the micelle inclines to deform into dumbbell due to the additional curvature originating in the gathering of asymmetric dimer particles onto the interface of the micelle. The present study on the deformation of micelles is useful to understand the possible shape variation in the course of cell division/fusion.

关键词： Dimer particle Copolymer micelle Deformation Self consistent field theory Density function theory.

Multiferroicity in B-site ordered double perovskite Y_2MnCrO_6

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Chinese Physics B 2014年第11期23卷 523-526页

作者：房勇颜士明乔文王伟王敦辉都有为 National laboratory of solid state Microstructures and Key laboratory of Nanomaterials of Jiangsu Province Nanjing University

Double perovskite manganite Y2MnCrO6 ceramic Novel multiferroic properties are displayed with respect is synthesized and its multiferroic properties are investigated. to other multiferroics, such as high ferroelectric phase transi- tion temperature, and the coexistence of ferrimagnetism and ferroelectricity. Moreover, the ferroelectric polarization of Y2MnCrO6 below the magnetic phase temperature can be effectively tuned by an external magnetic field, showing a re- markable magnetoelectric effect. These results open an effective avenue to explore magnetic multiferroics with spontaneous magnetization and ferroelectricity, as well as a high ferroelectric transition temperature.

关键词： magnetism ferroelectricity magnetoelectric effect multiferroics

Multiple sign reversals of the exchange bias field in polycrystalline SmCr_(0.9)Fe_(0.1)O_3

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Chinese Physics B 2014年第12期23卷 453-457页

作者：房勇颜士明龚元元朱卫利曹庆琪王敦辉都有为 Jiangsu Key laboratory for Nano Technology and National laboratory of solid state Microstructures Nanjing University

We synthesize the perovskite compound Sm Cr0.9Fe0.1O3 by the sol–gel method and investigate its exchange bias properties through thermomagnetic and isothermal magnetization measurements. The sign reversals of the exchange bias field are observed at the magnetization compensation temperatures 29.6 K and 96.2 K. It is demonstrated that the occurrence of the exchange bias originates from the antiferromagnetic coupling between the Cr-rich and Fe–Cr regions, of which the net magnetization is temperature-dependent. These results imply that there are potential applications in single systems with sign reversals of both magnetization and exchange bias.

关键词： magnetism antiferromagnetic exchange bias

Effects of the Wetting Particles on Phase Separation of Binary Mixtures

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Chinese Physics Letters 2000年第11期17卷 824-826页

作者： LIU Ji-Wen MA Yu-Qiang National laboratory of solid state Microstructures Nanjing UniversityNanjing 210093

We study phase separation of binary mixtures in the presence of mobile particles by the lattice Monte Carlo *** presence of mobile particles changes the morphology of the domain growth,in agreement with earlier experimental *** varying the wetting interaction strength,we can control the speed of phase separation,and find a critical wetting strength beyond which the growth of the domains slows *** propose a novel scaling function which describes the growth of the domain size L(t)as a function of *** suggests an applicable way to tune the speed of phase separation by the coupling between the phase decomposition and the mobile particle-wetting process.

关键词： strength separation phase

Large magnetoresistance in metamagnetic CoMnSi_(0.88)Ge_(0.12) alloy

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Chinese Physics B 2010年第3期19卷 513-516页

作者：张成亮王敦辉曹庆琪轩海成马胜灿都有为 National laboratory of solid state Microstructures and Key laboratory of Nanomaterials for Jiangsu Province Nanjing University

The magneto-transport properties are investigated in metamagnetic ***0.12 alloy. By applying a magnetic field or increasing temperature, a metamagnetic phase transition from antiferromagnetic to ferromagnetic is observed in this alloy. Around the metamagnetic phase transition, CoMnSi0.88Ge0.12 alloy exhibits a large and negative magnetoresistance effect （-32%） under a magnetic field of 20 kOe （1Oe = 79.5775 A/m）, which is ascribed to the spin-dependent scattering of conduction electrons.

关键词： metamagnetic magnetoresistance

Cl^(-)ions accelerating interface charge transfer in a Si/In_(2)S_(3) Faradaic junction photocathode for solar seawater splitting

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Science China Chemistry 2024年第9期67卷 2923-2929页

作者： Jun Luo Ruotong Bao Hongzheng Dong Ye Fu Dongjian Jiang Bo Wang Yuzhan Zheng Qiong Wang Wenjun Luo Zhigang Zou Eco-materials and Renewable Energy research Center(ERERC) Jiangsu Key Laboratory for Nano TechnologyNational Laboratory of Solid State MicrostructuresCollege of Engineering and Applied SciencesNanjing UniversityNanjing 210093China National laboratory of solid state Microstructures and Department of Physics Nanjing UniversityNanjing 210093China

Photoelectrocatalytic seawater splitting is a promising low-cost method to produce green hydrogen in a large *** effects of Cl^(-)ions in seawater on the performance of a photoanode have been reported in previous ***,few researches have been done on the roles of Cl^(-)ions in a ***,for the first time,we find that Cl^(-)ions in the electrolyte improve the photocurrent of a Si/In_(2)S_(3) photocathode by 50% at-0.6 V_(RHE).An in-situ X-ray photoelectron spectroscopy(XPS)characterization combined with the time-of-flight secondary-ion mass spectrometry by simulating photoelectrochemical conditions was used to investigate the interface charge transfer *** results suggest that there is an In_(2)^(+3)S_(3-x)(OH)_(2x)layer on the surface of In_(2)S_(3) in the phosphate buffer solution(PBS)electrolyte,which plays a role as an interface charge transfer mediator in the Si/In_(2)S_(3) *** In_(2)^(+3)S_(3-x)(OH)_(2x)surface layer becomes In_(2)^(+3)S_(3-x)(Cl)_(2x)in the PBS electrolyte with NaCl and accelerates the charge transfer rate at the In_(2)S_(3)/electrolyte *** results offer a new concept of regulating interface charge transfer mediator to enhance the performance of photoelectrocatalytic seawater splitting for hydrogen production.

关键词： solar hydrogen production interface charge transfer mechanism coupled electron and ion transfer in-situ XPS characterization In_(2)^(+3)S_(3-x)(OH)_(2x)surface layer