First‑principles study on electronic structure,optical and magnetic properties of rare earth elements X(X=Sc,Y,La,Ce,Eu)doped with two‑dimensional GaSe

The electronic structure,magnetic,and optical properties of two-dimensional(2D)GaSe doped with rare earth elements X(X=Sc,Y,La,Ce,Eu)were calculated using the first-principles plane wave method based on den-sity functional theory.The results show that intrinsic 2D GaSe is a p-type nonmagnetic semiconductor with an indi-rect bandgap of 2.6611 eV.The spin-up and spin-down channels of Sc-,Y-,and La-doped 2D GaSe are symmetric,they are non-magnetic semiconductors.The magnetic moments of Ce-and Eu-doped 2D GaSe are 0.908μ_(B)and 7.163μ_(B),which are magnetic semiconductors.Impurity energy levels appear in both spin-up and spin-down chan-nels of Eu-doped 2D GaSe,which enhances the probability of electron transition.Compared with intrinsic 2D GaSe,the static dielectric constant of the doped 2D GaSe increases,and the polarization ability is strengthened.The ab-sorption spectrum of the doped 2D GaSe shifts in the low-energy direction,and the red-shift phenomenon occurs,which extends the absorption spectral range.The optical reflection coefficient of the doped 2D GaSe is improved in the low energy region,and the improvement of Eu-doped 2D GaSe is the most obvious.

Effects of Fe_(2)O_(3) content on microstructure and mechanical properties of CaO-Al_(2)O_(3)-SiO_(2) system

The effects of Fe2O3 content on the microstructure and mechanical properties of the CaO-Al2O3-SiO2 system were investigated by differential thermal analysis（DTA）, X-ray diffraction（XRD）, scanning electron microscopy（SEM）, electron spin resonance（ESR）, and Mssbauer spectroscopy. The results show that the addition of Fe2O3 does not affect the main crystalline phase in the prepared glasses, but it reduces the crystallisation peak temperature, increases the crystallisation activation energy, and reduces the crystal granularity. The ESR results indicate that Fe2O3 can promote crystallization, as it leads to the phase separation of the CaO-Al2O3-SiO2 system due to axial distortion. Moreover, Fe2O3 alters the network structure of the CaO-Al2O3-SiO2 system, allowing Fe3＋ to enter octahedral sites that exhibit higher symmetry than tetrahedral sites. All of these factors are favourable to increasing the bending strength. The Mssbauer results reveal that there are two types of coordination for both Fe3＋ and Fe2＋ and the bending strength of the CaO-Al2O3-SiO2 system increases with the amount of six-coordinate Fe3＋. The increasing interaction between Fe3＋ and Fe2＋ can also enhance the bending strength of the CaO-Al2O3-SiO2 system. The microhardness of the CaO-Al2O3-SiO2 system was determined to be HV 896.9 and the bending strength to be 217 MPa under the heat treatment conditions of nucleation temperature of 700 °C and nucleation time of 2 h, crystallization temperature of 910 °C and crystallization time of 3 h.

Preparation of (SiFe) C DMS Based 4H-SiC Substrate

A diluted magnetic 4H-SiC has been prepared by implanting Fe ions into the substrate. Its Curie temperature reaches as high as 320K and its technology is compatible with current IC. Moreover, the process includes three annealing steps,named HNH annealing in this paper. Each step during this annealing has been analyzed. Comparisons have been made with different Fe concentrations and experimental results demonstrate that when the concentration of Fe is 0. 051, the Curie temperature is the highest. According to measurements, some explanation of this phenomenon is given.

Two—Electron Energy Spectrum in a Parabolic Quantum Dot Under a Magnetic Field

Two interacting electrons in a harmonic oscillator potential under the influence of a perpendicular homo-geneous magnetic field are considered. The energies of two-electron quantum dots with the electron-LO-phonon couplingas a function of magnetic field are calculated. Calculations are made by using the method of few-body physics withinthe effective-mass approximation. Our results show that the electron-LO-phonon coupling effect is very important insemiconductor quantum dots.

Application of Bipartite and Tripartite Entangled State Representations in Quantum Teleportation of Continuous Variables

We mostly investigate two schemes. One is to teleport a multi-mode W-type entangled coherent state using a peculiar bipartite entangled state as the quantum channel different from other proposals. Based on our formalism,teleporting multi-mode coherent state or squeezed state is also possible. Another is that the tripartite entangled state is used as the quantum channel of controlled teleportation of an arbitrary and unknown continuous variable in the case of three participators.

How to realize a negative refractive index material at the atomic level in an optical frequency range?

The theoretical mechanism for realizing a negative refractive index material in an optical frequency range with an atomic gas system of electromagnetically induced transparency (EIT) is studied. It is shown that under certain conditions such a dense gas can exhibit simultaneously negative permittivity and negative permeability, and negligibly small loss.

Dynamics analysis of vibration process in Particle Impact Noise Detection

Particle Impact Noise Detection (PIND) test is a reliability screening technique for hermetic device that is prescribed by MIL-PRF-39016E. Some test conditions are specified, although MIL-PRF-39016E did not specify how to obtain these condi- tions. This paper establishes the dynamics model of vibration process based on first order mass-spring system. The corresponding Simulink model is also established to simulate vibration process in optional input excitations. The response equations are derived in sinusoidal excitations and the required electromagnetic force waves are computed in order to obtain a given vibration and shock accelerations. Last, some simulation results are given.

Connection between Physical Properties in Homologous Series of Molecular Systems

The connections between different physical-chemical properties in homologous molecular series are analyzed from the quantum-mechanic and the algebraic theory points of view and are explained by influence of the gage to the quantum electronic continuum. The connection between quantum and macroscopic properties of the substances is confirmed in homologous series of n-alkanes. Linear correlation between the coefficient of magnetization and energy of the highest occupied molecular orbital in homologous series of n-alkanes C2-C10 is established. The connection between diamagnetic and electronic characteristics of n-alkanes with the temperatures of the first order phase transitions （melting point） and other physical-chemical properties were discovered. The nature of interconnection between critical and diamagnetic properties of n-alkanes C2-C10 and results of previous works allow to suppose significant role of the spin interactions in electronic continuum states along the process of the first order phase transitions.

Analytical structure of Hermite Gaussian beam in far field

Based on the vectorial structure of electromagnetic beam and the method of stationary phase, the analytical structure of Hermite Gaussian beam in far field is presented. The structural energy flux distributions are also investigated in the far field. The structural pictures of some Hermite Gaussian beams are depicted in the far field. As the structure of Hermite Gaussian beam is dominated by the transverse mode numbers and the initial transverse Gaussian half width, it is more complex than that of Gaussian beam. The ratios of the structural energy fluxes to the whole energy flux are independent of the transverse mode numbers and the initial transverse Gaussian half width. The present research reveals the internal vectorial structure of Hermite Gaussian beam from other viewpoint.

Optical properties and magnetic properties of antisite-disordered Ni_(1-x)Co_xCr_2O_4 spinels

From the UV?Vis absorption spectra,the FT-IR absorption spectra and the Raman spectra,it is deduced that Co ionsprimarily occupy the tetrahedral(A)site,with a minor number of them entering into the octahedral(B)site in the Ni1?xCoxCr2O4compounds.The origin of the position disorder of the Co ions is consistent with the similar ionic radii of the Co ion(0.65?)and theCr ion(0.62?)at B site.The FT-IR peak at about510cm?1shifts towards high frequency side with the increasing cobalt content.Itis resulted from the reduction of the cation?oxygen distance in the octahedron by the replacement of the Ni2+with the Co2+ions.Themagnetic measurement shows that Curie temperatures(TC)are75and90K for the compounds with x=0.2and0.8,respectively.

Modeling and validation of magnetic tunnel junction device

We have presented here a simple model of magnetic tunnel junction(MTJ)device and the proposed MTJ model is utilizedfor validation purpose and also to study its tunnel magneto-resistance(TMR)effect by both simulation and experimentalmethod using an operational amplifier(OPAMP)based inverting amplifier.Experimental results substantiates both the simulatedand theoretical outcomes.

Nonlinear Temperature Dependence of Magnetization of Two-Band Superconductors Near Upper Critical Field

Temperature dependence of the magnetization M （T） of two-band superconductors is studied in the vicinity of upper critical field He2 by using a two-band Ginzburg-Landau （GL） theory. It is shown that magnetization M（T） has a nonlinear character due to positive curvature of upper critical field Hc2（T） and temperature dependence of effective Ginzburg-Landau parameter Neff（T）. The results are shown to be in qualitative agreement with experimental data for the superconducting magnesium diboride, MgB2.

Effect of Sb_2O_3-doped on optical absorption of ZnO thin film

Sb2O3 doped ZnO thin film was prepared by RF magnetron sputtering technique.The influence of Sb2O3 on the structure and the optical absorption of ZnO thin film was studied by XPS,XRD apparatuses and UV-Vis spectrophotometer.The results show that doped Sb2O3 has affected atomic and electronic structures,growth modes of crystal grains and optical absorption of ZnO.The element Sb exists in many forms in the film including transpositional atoms and compounds such as Sb2O3,Zn7Sb2O 14 etc.ZnO crystal grains grow in mixing directions.The lattice relaxation and the content of second phases increase when more Sb is doped.The UVA absorption of doped ZnO thin film increases obviously.The ultraviolet absorption peak narrows,absorption intensity increases,the absorption margin becomes steep and moves to shorter wavelength of about 5 nm,and the visible absorption increases in some sort.

A Scheme of Conditional Quantum Phase Gate for Dissipative Cavity QED System

We propose a scheme to implement a two-qubit conditional quantum phase gate via a single mode cavity and a cascade four-level atom assisted by a classical laser. The quantum information is encoded.on the Flock states of the cavity mode and the two metastable ground states of the atom. Even under the condition of systematic dissipations, this scheme can also be realized with fidelity of 98.6% and success probability of 0.767.

Entanglement Evolution of a 2-Qutrit System Interacting with a Fermionic Bath

Based on the algebraic entanglement measure proposed [G. Vidal et al., Phys. Rev. A 65 (2002) 032314],we study the entanglement evolution of both pure quantum states and mixed ones of 2-qutrit system in a symmetrybroken environment consisting of a fermionic bath. Entanglement of states will decrease or remain constant under the influence of environment, and the class of states which remain unchanged has been found out.

Electronic Structure Magnetic Properties and Optical Properties of Co-doped AIN from First Principles

The electronic structure, magnetic properties, and optical properties of Co-doped AIN are investigated based upon the Perdew-Burke-Ernzerhof form of generalized gradient approximation within the density functional theory. The band gaps narrowing of AI1-x Cox N are found with the increase of Co concentrations. The analyses of the band structures and density of states show that AI1-xCoxN alloys exhibit a halfometallie character. Moreover, we have succeeded in demonstrating that Co doped AIN system in x = 0.125 is always antiferromagnetie, which is in good agreement with the experimental results. Besides, it is shown that the insertion of Co atom leads to redshift of the optical absorption edge. Finally, the optical constants of pure A1N and AI1-xCoxN alloy, such as loss function, refractive index and reflectivity, are discussed.

Effects of Electric and Magnetic Fields on Pure Dephasing of Exciton Qubits

In a two-dimensional quantum dot （QD） with parabolic confinement potential, we investigate pure dephasing due to deformation potential exciton-bulk longitudinal acoustic phonons （LAP） interaction for exciton qubits under the influence of external static electric and magnetic fields by adopting the full quantum-mechanical method of Kunihiro Kojima and Akihisa Tomita. The wave function is found and the dependence of the pure dephasing factor on the confinement length of the QD and time and temperature is discussed. We find the external electric and magnetic fields have important effects on pure dephasing of exciton qubits because exciton-LAP interaction increases, leading to more pure dephasing.

Theoretical Studies of Electron Paramagnetic Resonance Parameters for Cr^4＋ Ions in Ca2GeO4 Crystals

The electron paramagnetic resonance (EPR) parameters (zero-Geld splitting Dand g factors g_‖, g_⊥) of Cr~(4+) ions in Ca_2 GeO_4 crystals have been calculated from thecomplete high-order perturbation formulas of EPR parameters for a 3d~2 ion in trigonal MX_4clusters. In these formulas, in addition to the contributions to EPR parameters from the widely usedcrystal-field (CF) mechanism, the contributions from the charge-transfer (CT) mechanism (which areoften neglected) are included. From the calculations, it is found that for the high valence state3d~n ions in crystals, the reasonable explanation of EPR parameters (in particular, the g factors)should take both the CF and CT mechanisms into account.

Classical Theory of Hot－Electron Transport in Electric and Magnetic Fields

Balance equation approach to the hot-electron transport in electric and magnetic fields is reformulated. The balance equations are re-derived from the Boltzmann equation. A new expression for the distribution function is reported in the present paper. It is homogeneous steady solution of the Boltzmann equation in constant relaxation time approximation. It holds when or . As an example, the mobility of 2D electron gas in the GaAs-AlGaAs heterojunction is computed as a function of electric field and magnetic field.

Vacuum-Induced Abelian and Non-Abelian Gauge Potentials in Cavity Quantum Electrodynamics

Gauge potential plays an important role in exploring exotic phenomena in the single- and many-body quantum systems.In this paper,we propose a scheme to create both new Abelian and non-Abelian gauge potentials by adiabatically controlling the degenerate Dicke model in cavity quantum electrodynamics.It is shown that a non-Abelian gauge potential is achieved only for a single atom,whereas an Abelianizen diagonal gauge potential is realized for the atomic ensemble.More importantly,two interesting quantum phenomena such as the geometric phase and the magnetic monopole induced by our created gauge potentials are also predicted.The possible physical realization is presented in the macroscopic circuit quantum electrodynamics with the Cooper pair boxes,which act as the artificial two-level atoms controlled by the gate voltage and the external magnetic flux.