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Anisotropic localization behavior of graphene in the presence of diagonal and off-diagonal disorders

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Chinese physics B 2013年第12期22卷 416-421页

作者：王莉敏拾邵聪章维益 The National Laboratory of solid state Microstructures and the department of physics Nanjing University

Anisotropic localization of Dirac fermions in graphene along both the x and y axes was studied using the transfer-matrix method. The two-parameter scaled behavior around the Dirac points was observed along the x axis with off-diagonal disorder. In contrast, the electronic state along the y axis with armchair edges was delocalized, which can be described well by single parameter scaling theory. This implies that the breakdown of the single-parameter scaling is related to the zigzag edge along the x axis. Furthermore, dimerization induced by the substrate suppresses the two-parameter scaling behavior along the x axis and preserves the delocalized state along the y axis. Our results also demonstrate anisotropic localization in graphene with diagonal disorder that can be tuned by dimerization.

关键词： anisotropic localization graphene dimerization

Martensitic transformation and related magnetic effects in Ni-Mn-based ferromagnetic shape memory alloys

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Chinese physics B 2013年第7期22卷 1-10页

作者：王敦辉韩志达轩海成马胜灿陈水源张成亮都有为 National Laboratory of solid state Microstructures Department of PhysicsNanjing University

Ferromagnetic shape memory alloys, which undergo the martensitic transformation, are famous multifunctional materials. They exhibit many interesting magnetic properties around the martensitic transformation temperature due to the strong coupling between magnetism and structure. Tuning magnetic phase transition and optimizing the magnetic effects in these alloys are of great importance. In this paper, the regulation of martensitic transformation and the investigation of some related magnetic effects in Ni–Mn-based alloys are reviewed based on our recent research results.

关键词： magnetocaloric effect magnetoresistance effect exchange bias magnetoelectric effect

The basis of organic spintronics: Fabrication of organic spin valves

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Chinese physics B 2014年第1期23卷 21-27页

作者：陈彬彬姜生伟丁海峰蒋正生吴镝 National Laboratory of solid state Microstructures and department of physics Nanjing University

Organic spintronics focuses on utilizing the spin degree of freedom in organic materials because of the long spin relaxation time. The vertical organic spin valve(OSV) is a typical sample structure used to study the spin transport phenomena. However, the fabrication of high quality OSVs is difficult, which results in controversial experiment results and hence hinders the development of organic spintronics. In this work, we describe our recent study on the fabrication of typical vertical organic spin valves, La0.67Sr0.33MnO3(LSMO)/Alq3/Co. The LSMO bottom electrodes are annealed to obtain an atomically smooth surface and improved magnetic properties. The top Co electrodes are deposited by an indirect deposition method to reduce the interfusion between Co and Alq3. The controlled fabrication process provides much better performance and sample yield of OSVs.

关键词： organic spintronics organic spin valves magnetoresistance

Theoretical study of interactions between striated cylindrical particles and membrane

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Chinese physics B 2015年第8期24卷 624-631页

作者：王晶晶冯佳伟任春来 National Laboratory of solid state Microstructures and department of physics Nanjing University

The interaction of nanoparticles with cell membranes is of great importance because of their potential biomedical applications. In this paper, we investigate the adhesion of stripe-patterned cylinders to a fluid membrane with a full consideration of the Helfrich free energy. Three situations are considered: one striated cylindrical particle, two pure cylindrical particles, and two Janus cylindrical particles. It is found that, with the adhesion of a single sparse striated cylinder, there are a variety of steady-states with energy barriers and the stable state is determined by the pattern of the cylinder. However,when the particle is densely striped, it has no effect on the stable state. By comparing the wrapping degree of two cylindrical particles with that of a single cylindrical particle, we find that two pure cylindrical particles can promote or suppress their interaction with the membrane under different situations. However, two Janus cylindrical particles can only inhibit their interaction with the membrane. Besides, this interaction is related to a first-order transition which is a shallow-to-deep wrapping transition for two pure cylinders while it is a shallow-to-half wrapping transition for two Janus cylinders. Furthermore, the position where the transition happens as a function of adhesion energy is given for fixed membrane tension and the precondition of the transition is presented.

关键词： Helfrich free energy striated particles membrane wrapping

Structural and dielectric properties of doped ferrite nanomaterials suitable for microwave and biomedical applications

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Progress in Natural Science:Materials International 2015年第5期25卷 419-424页

作者： Imran Sadiq Shahzad Naseem Muhammad Naeem Ashiq M.A.Khan Shanawer Niaz M.U.Rana Centre of Excellence in solid state physics University of the Punjab institute of Chemical Sciences Bahauddin Zakariya University department of physics BUITEMS 4. Department of Physics University of Sargodha

The sol-gel auto-combustion method was adopted to synthesize nanomaterials of single-phase X-type hexagonal ferrites with the composition of Sr;Gd;Ni;Fe;Cd;O;（x=0.00,0.02,0.04,0.06,0.08,0.10 and y = 0,0.1,0.2,0.3,0.4,0.5）.The structural properties were carried out by XRD analysis and the lattice parameters show variation with the doping of *** average particle size measured by TEM was in the range of 8-10 nm which is beneficial in obtaining suitable signal-to-noise ratio in recording media and biomedical *** room temperature resistivity enhanced with the increase of the dopant *** increase in resistivity indicates that the synthesized materials can be considered good for the formation of the multilayer chip inductors（MLCIs） as well as for the reduction of eddy current *** dielectric constant decreased with the increase in the frequency which is the general reported trend of the hexagonal ferrites and can be explained on the basis of Koop’s theory and Maxwell-Wagner *** abnormal dielectric behavior indicates the formation of small polarons in the *** maximum value of tangent loss at low frequencies reflects the application of these materials in medium frequency devices（MF）.

关键词： Sol–gel Nanocrystalline materials Thermal properties Electrical properties Dielectric properties

The origin of blue photoluminescence from nc-Si/SiO_2 multilayers

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Chinese physics B 2008年第1期17卷 303-306页

作者：马忠元郭四华陈德媛魏德远姚瑶周江黄锐李伟徐骏徐岭黄信凡陈坤基冯端 state Key Laboratory of solid state Microstructures and department of physics Nanjing University

Intensive blue photoluminescence （PL） was observed at room temperature from the nanocrystalline-Si/SiO2 （nc-Si/SiO2） multilayers （MLs） obtained by thermal annealing of SiO/SiO2 MLs for the first time. By controlling the size of nc-Si formed in SiO sublayer from 3.5 to 1.5 nm, the PL peak blueshifts from 457 to 411 nm. Combining the analysis of TEM, Raman and absorption measurement, this paper attributes the blue PL to multiple luminescent centres at the interface of nc-Si and SiO2.

关键词： PL nc-Si Raman spectroscopy

Squeezing in the Thermal Jaynes-Cummings Model

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Chinese physics Letters 1996年第6期13卷 432-435页

作者： XIE Rui-hua ZOU You-tao LIU Dun-huan department of physics Nanjing UniversityNanjing 210008 department of physics Wuhan UniversityWuhan 430072 National Laboratory of solid state Microstructures Institute for Solid State Physics Center for Advanced Studies in Science and Technology of Microstructures Nanjing UniversityNanjing 210008

We have studied the influence of thermal photons on the symmetry between the field and atomic squeezing(SFAS)exposed in the resonant vacuum-field Jaynes-Cummings model with an initially coherent *** have shown that when the number of thermal photons(Nav)is less than 0.01,the SFAS is not sensitive to the presence of thermal photons;when Nav≥0.01,the broken SFAS can be seen;when Nav≥0.1,the squeezed atom cannot radiate a squeezed field any ***,we have discussed the possibility of detection of the boken symmetry in superconducting maser cavity.

关键词： symmetry Cummings resonant

4D spinless topological insulator in a periodic electric circuit

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National Science Review 2020年第8期7卷 1288-1295页

作者： Rui Yu Y.X.Zhao Andreas P.Schnyder School of physics and Technology Wuhan University National Laboratory of solid state Microstructures and department of physics Nanjing University Collaborative Innovation Center of Advanced Microstructures Nanjing University Max-Planck-institute for solid state Research

According to the mathematical classification of topological band structures, there exist a number of fascinating topological states in dimensions larger than three with exotic boundary phenomena and interesting topological responses. While these topological states are not accessible in condensed matter systems, recent works have shown that synthetic systems, such as photonic crystals or electric circuits, can realize higher-dimensional band structures. Here, we argue that, because of its symmetry properties, the 4D spinless topological insulator is particularly well suited for implementation in these synthetic systems. We explicitly construct a 2D electric circuit lattice, whose resonance frequency spectrum simulates the 4D spinless topological insulator. We perform detailed numerical calculations of the circuit lattice and show that the resonance frequency spectrum exhibits pairs of 3D Weyl boundary states, a hallmark of the nontrivial topology. These pairs of 3D Weyl states with the same chirality are protected by classical time-reversal symmetry that squares to +1, which is inherent in the proposed circuit lattice. We also discuss how the simulated 4D topological band structure can be observed in experiments.

关键词： topological circuit 4D topological states 4D topological Hall effect second Chern number Weyl states

First-Principles Study of Lithium and Sodium Atoms Intercalation in Fluorinated Graphite

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Engineering 2015年第2期1卷 243-246页

作者： Fengya Rao Zhiqiang Wang Bo Xu Liquan Chen Chuying Ouyang department of physics Jiangxi Normal University Laboratory for solid state Ionics Institute of Physics Chinese Academy of Sciences

The structure evolution of fluorinated graphite （CFx） upon the Li/Na intercalation has been studied by first- principles calculations. The Li/Na adsorption on single CF layer and intercalated into bulk CF have been calculated. The better cycling performance of Na intercalation into the CF cathode, comparing to that of Li intercalation, is attributed to the different strength and characteristics of the Li-F and Na-F interactions. The interactions between Li and F are stronger and more localized than those between Na and E The strong and localized Coulomb attraction between Li and F atoms breaks the C-F bonds and pulls the F atoms away, and graphene sheets are formed upon Li intercalation.

关键词： first-principles Li/Na rechargeable batteries fluorinated graphite.