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1.  Single-particle spectral function of the Hubbard chain: frustration induced  
   王竞  EnricoArrigoni《中国物理 B》,2009年第18卷第6期
   The one-electron spectral function of a frustrated Hubbard chain is computed by making use of the cluster perturbation theory. The spectral weight we found turns out to be strongly dependent on the frustrating next-nearest-neighbor hopping t. A frustration induced pseudogap arises when the system evolves from a gapful Mott insulator to a gapless conductor for an intermediate value of the frustration parameter |t|. Furthermore,the opening of a pseudogap in the density of states already in the metallic side leads to a continuous opening of the true gap in the insulator. For the hole-doped case,the pseudogap is pinned at the Fermi energy, while the Mott gap is shifted in energy with increasing Hubbard interaction U. The separation of the pseudogap and Mott gap in the hole-doped system demonstrates the validity of the existence of a pseudogap.    

2.  Observation of Two Quasi—Static Wings of Laser—Induced Collision Energy Transfer  
   郑瑞华 陈德应 等《中国物理快报》,2002年第19卷第1期
   We investigate experimentally laser-induced collision energy transfer for transitions both from Eu(6s6p)^8 P9/2 to Sr(5s10s)^1So and from Eu(6s6p)^s-P7/2 to Sr(5s8d)^1D2.Two quasi-static wings are observed in their excited function spectra.By using two dipole-dipole interactions,a spectral line from numerical calculation is consistent with the experimental line in two quasi-static wings.    

3.  Electron Spin Pairing and Excitations in High—Tc Superconductors  
   郭卫 韩汝珊 等《中国物理快报》,2002年第19卷第11期
   Effective spin coupling between conduction electrons mediated by local Cu moments in the doped CuO2 plane may induce the instability of the normal states of conduction electrons and pairing at Cu stes,where the superexchange interaction between local moments influenced by hole doping has been found to be Ising-like in recent experiments.By a mean field approach,we show that spin pairing and strong pair-pair interaction in the doped antiferromagnetic ordered Ising-like CuO2 plane gives rise to high-temperature superfluid condensation and the exceptional features of quasi-particle excitation in cuprates such as spin gap,pseudogap,and the linear temperature dependence of resistivity ρab in the normal states.    

4.  Effect of interstitial air holes on Bragg gratings in photonic crystal fibre with a Ge-doped core  
   张慧嘉  李曙光  侯蓝田《中国物理 B》,2009年第18卷第2期
   The effect of interstitial air holes on Bragg gratings in photonic crystal fibre (PCF) with a Ge-doped core is numerically investigated by using the beam propagation method (BPM). It is shown that the interstitial air holes (IAHs) can make Bragg resonance wavelength λ B shift a little towards short wavelengths and increase λ B λ 1 (the wavelength spacing between the main peak with Bragg resonance wavelength λ B and the first side peak with wavelength λ 1 ) and the coupling coefficient κ of Bragg resonance. Moreover, when the ratio of air hole diameter (d) to pitch (Λ), d/Λ, is small, IAHs can suppress the cladding mode resonance. When d/Λ is large, IAHs increase the number of mode that could strongly interact with the fundamental mode. By comparing the transmission spectral characteristics of PCF-based fibre Bragg grating (FBG) with IAHs with those without IAHs at the same air-filling fraction, it is clarified that the change of transmission spectral characteristics of PCF-based FBG with IAHs is not due to a simple change in air-filling fraction. It is also closely related to the distribution of interstitial air holes.    

5.  Magnetic interactions in a proposed diluted magnetic semiconductor(Ba_(1-x)K_x)(Zn_(1-y)Mn_y)_2P_2  
   杨焕成  刘凯  卢仲毅《中国物理 B》,2018年第6期
   By using first-principles electronic structure calculations, we have studied the magnetic interactions in a proposed BaZn_2P_2-based diluted magnetic semiconductor(DMS). For a typical compound Ba(Zn_(0.944)Mn_(0.056))_2P_2 with only spin doping, due to the superexchange interaction between Mn atoms and the lack of itinerant carriers, the short-range antiferromagnetic coupling dominates. Partially substituting K atoms for Ba atoms, which introduces itinerant hole carriers into the p orbitals of P atoms so as to link distant Mn moments with the spin-polarized hole carriers via the p–d hybridization between P and Mn atoms, is very crucial for the appearance of ferromagnetism in the compound. Furthermore, applying hydrostatic pressure first enhances and then decreases the ferromagnetic coupling in(Ba0.75 K0.25)(Zn_(0.944)Mn_(0.056))_2P_2 at a turning point around 15 GPa, which results from the combined effects of the pressure-induced variations of electron delocalization and p–d hybridization. Compared with the BaZn_2 As_2-based DMS, the substitution of P for As can modulate the magnetic coupling effectively. Both the results for BaZn_2 P_2-based and BaZn_2As_2-based DMSs demonstrate that the robust antiferromagnetic(AFM) coupling between the nearest Mn–Mn pairs bridged by anions is harmful to improving the performance of these Ⅱ–Ⅱ–Ⅴ based DMS materials.    

6.  Near-infrared downconversion in Eu2+ and Pr3+ co-doped KSrPO4 phosphor  
   孙家跃  孙翊宁  朱吉成  曾军辉  杜海燕《中国物理 B》,2013年第5期
   A novel near-infrared (NIR) downconversion (DC) phosphor KSrPO4 :Eu2+ , Pr3+ is synthesized by the conventional high temperature solid-state reaction. The Eu2+ acts as an efficient sensitizer for Pr3+ in the KSrPO4 host. With broad-band near-ultraviolet light excitation induced by the 4f→5d transition of Eu2+ , the characteristic NIR emission of Pr3+ , peaking at 974 nm and 1019 nm due to 3P0 → 1G4 and 1G4 → 3H4 transitions, is generated as a result of the energy transfer from Eu2+ to Pr3+ . The luminescence spectra in both the visible and the NIR regions and the decay lifetime curves of Eu2+ prove the energy transfer from Eu2+ to Pr3+ . This Eu2+ and Pr3+ co-doped KSrPO4 phosphor may be a promising candidate to modify the spectral mismatch behavior of crystalline solar cells and sunlight.    

7.  Filling dependence of correlation exponents and metal-Mott insulator transition in strongly correlated electron systems  
   林明喜  祁胜文《中国物理 B》,2010年第19卷第12期
   Using a universal relation between electron filling factor and ground state energy,this paper studies the dependence of correlation exponents on the electron filling factor of one-dimensional extended Hubbard model in a strong coupling regime,and demonstrates that in contrast to the usual Hubbard model(gc = 1/2),the dimensionless coupling strength parameter g c heavily depends on the electron filling,and it has a "particle-hole" symmetry about electron quarter filling point.As increasing the nearest neighbouring repulsive interaction,the single particle spectral weight is transferred from low energy to high energy regimes.Moreover,at electron quarter filling,there is a metal-Mott insulator transition at the strong coupling point gc = 1/4,and this transition is a continuous phase transition.    

8.  Switchable Multi-Wavelength Erbium-Doped Fiber Lasers based on a Mach-Zehnder Interferometer Using a Twin-Core Fiber  
   冯素春  许鸥  鲁韶华  简水生《中国物理快报》,2009年第26卷第6期
   A switchable multi-wavelength erbium-doped fiber ring laser based on a compact in-fiber Mach-Zehnder interferometer comb filter at room temperature is presented. The comb filter is formed by splicing a section of twin-core fiber between two single mode fibers. By adjusting the states of the polarization controller appropriately, the laser can be made to operate in stable single-, dual- and three-wavelength lasing states. The operation principle is based on spectral hole burning induced by the saturated effect and polarization hole burning.    

9.  The electronic and magnetic properties of (Mn,C)-codoped ZnO diluted magnetic semiconductor  
   赵龙  芦鹏飞  俞重远  马世甲  丁路  刘建涛《中国物理 B》,2012年第21卷第9期
   The electronic and magnetic properties of (Mn,C)-codoped ZnO are studied in the Perdew-Burke-Ernzerhof form of generalized gradient approximation of the density functional theory. By investigating five geometrical configurations, we find that Mn doped ZnO exhibits anti-ferromagnetic or spin-glass behaviour, and there are no carriers to mediate the long range ferromagnetic (FM) interaction without acceptor co-doping. We observe that the FM interaction for (Mn,C)-codoped ZnO is due to the hybridization between C 2p and Mn 3d states, which is strong enough to lead to hole-mediated ferromagnetism at room temperature. Meanwhile, we demonstrate that ZnO co-doped with Mn and C has a stable FM ground state and show that the (Mn,C)-codoped ZnO is FM semiconductor with super-high Curie temperature (T C = 5475 K). These results are conducive to the design of dilute magnetic semiconductors with codopants for spintronics applications.    

10.  The magnetoelectric properties of A- or B-site-doped PbVO3 films: A first-principles study  
   陈星源  陈丽娟  赵宇军《中国物理 B》,2013年第8期
   We employ first-principles calculations to study the magnetic and ferroelectric properties of PbVO3 with A (XA = Ca, Sr, Bi, Ba, and La) or B (XB = Ti, Cr, Mn, Fe, Co, Ni, and Cu) site dopants, with the aim of ascertaining a large ferroelectric polarization and a long magnetic order, or even a macro fen'i/ferromagnetism, which is critical to their potential applications in magnetoelectronic devices. It is found that PbTXAVsO24 (XA =Ca, Sr, and Ba,) are inclined to maintain the spin glass and large ferroelectric polarization. The degenerated G- and C-antiferromagnetic (AFM) couplings in the ideal PbVO3 are broken up, accompanied by the loss of ferroelectric properties, when La or Bi is doped at the A site. In contrast, the above-mentioned 3d transition elements doped at the B site of PbVO3 could induce remnant magnetic moments and preserve the large ferroelectric polarization, except for Ni and Cu. The Fe or Cr at the B site clearly remove the degenerated G- and C-AFM coupling, but the nonmagnetic Ti cannot do so. For the Mn, Co, Ni, or Cu doped at the B sites, even the two-dimensional AFM ordering in PbVO3 is destabilized. The various doping effects are further discussed with inner strain and charge transfer.    

11.  Structural and electronic properties of atomic oxygen adsorption on Cu(111) surface:A first-principles investigation  
   MA LiangCai  ZHANG JianMin  XU KeWei《中国科学:物理学 力学 天文学(英文版)》,2013年第3期
   By using the first-principles calculations,we have systematically investigated the adsorption of atomic oxygen on Cu(111) surface for a wide range of coverages Θ(from 0.11 to 1.00 ML) and adsorption sites.We found that the fcc-hollow site is the most stable site for oxygen adsorption.The adsorption energy decreases with increasing oxygen coverage due to the increasing repulsive interaction in the overlayer O adatoms.Except for coverage of 1.00 ML,the oxygen-induced lateral relaxations and bucklings are found in the outermost three Cu layers,and the hillock-like as well as ridge-like bucklings are also found for Θ=0.25 ML and Θ=0.75 ML as well as Θ=0.50 ML,respectively.With an increasing oxygen coverage,the work function increases and the surface dipole moment decreases.Electron transfer from the first layer Cu atoms to O adatoms indicates the O-Cu bond having some degree of ionic character,while the hybridization between O 2p and Cu 3d orbitals implies that it also has some degree of covalence character.Moreover,with the increasing oxygen coverage,more Cu 3d and O 2p states are empty thus weakening the binding of O/Cu(111) system,but increase in the PDOS at the Fermi level.This implies an enhancement in the metallic character of the O/Cu(111) system.    

12.  Magnetic properties of Mn-doped ZnO diluted magnetic semiconductors  
   刘学超  张华伟  张涛  陈博源  陈之战  宋力昕  施尔畏《中国物理 B》,2008年第17卷第4期
   A series of Mn-doped ZnO films have been prepared in different sputtering plasmas by using the inductively coupled plasma enhanced physical vapour deposition. The films show paramagnetic behaviour when they are deposited in an argon plasma. The Hall measurement indicates that ferromagnetism cannot be realized by increasing the electron concentration. However, the room-temperature ferromagnetism is obtained when the films are deposited in a mixed argon-nitrogen plasma. The first-principles calculations reveal that antiferromagnetic ordering is favoured in the case of the substitution of Mn^2+ for Zn^2+ without additional acceptor doping. The substitution of N for O (NO^-) is necessary to induce ferromagnetic couplings in the Zn-Mn-O system. The hybridization between N 2p and Mn 3d provides an empty orbit around the Fermi level. The hopping of Mn 3d electrons through the empty orbit can induce the ferromagnetic coupling. The ferromagnetism in the N-doped Zn-Mn-O system possibly originates from the charge transfer between Mn^2+ and Mn^3+ via NO^-, The key factor is the empty orbit provided by substituting N for O, rather than the conductivity type or the carrier concentration.    

13.  In-plane optical spectral weight redistribution in the optimally doped Ba_(0.6)K_(0.4)Fe_2As_2 superconductor  
   许兵  戴耀民  肖宏  R. P. S. M. Lobo  邱祥冈《中国物理 B》,2014年第8期
   We performed detailed temperature-dependent optical measurements on optimally doped Ba0.6K0.4Fe2As2 single crystal, We examine the changes of the in-plane optical conductivity spectral weight in the normal state and the evolution of the superconducting condensate in the superconducting state. In the normal state, the low-frequency spectral weight shows a metallic response with an arctan (T) dependence, indicating a T-linear scattering rate behavior for the carriers. A high energy spectral weight transfer associated with the Hund's coupling occurs from the low frequencies below 4000 cm^-1 5000 cm^-1 to higher frequencies up to at least 104 cm^-1. Its temperature dependence analysis suggests that the Hund's coupling strength is continuously enhanced as the temperature is reduced. In the superconducting state, the FGT sum rule is conserved according to the spectral weight estimation within the conduction bands, only about 40% of the conduction bands participates in the superconducting condensate indicating that Ba0.6K0.4Fe2As2 is in dirty limit.    

14.  INFLUENCE OF OXYGEN UPON THE SUPERCONDUCTIVITY OF THE Pb-DOPED 2223 SUPERCONDUCTOR  
   陈廷国  沈忠哲  谢晓明  陈源《中国物理》,1993年第2卷第9期
   The influences of oxygen content (by quenching from different temperatures in air or oxygen) and its re-distribution (by annealing in nitrogen at 200℃) on Tc and room temperature resistivity were studied. It was found that Tc as a function of oxygen content or charge carrier concentration exhibits a maximum. Upon oxygen re-distribution, the room temperature resistivity would always inclose but Tc would change in a complicated way. Tc increases for the oxygen-rich state and decreases for the oxygen-deficient state Internal friction measurements showed that there are two kinds of oxygen defects in the Bi2-O2 layers. One is the isolated oxygen interstitials and the other is oxygen vacancies on the excess oxygen chains. It is proposed that the isolated interstitial oxygen will produce a set of impurity states near the Fermi level, and will create holes on the Cu3d-O2p band through charge transfer from the Cu3d-O2p band to the impurity states. The content of the isolated oxygen interstitial is believed to be the major factor for determining the charge carrier concentration. Variation of Tc and room temperature resistivity with oxygen re-distribution is sat-isfactorily explained as to be induced by combination of oxygen interstitials with oxygen vacancies on the excess oxygen-chains.    

15.  Magnetic properties of Mn-doped GaN with defects:ab-initio calculations  
   E. Salmani  A. Benyoussef  H. Ez-Zahraouy  E. H. Saidi《中国物理 B》,2011年第20卷第8期
   According to first-principles density functional calculations,we have investigated the magnetic properties of Mn-doped GaN with defects,Ga 1-x-y V Gx Mn y N 1-z-t V Nz O t with Mn substituted at Ga sites,nitrogen vacancies V N,gallium vacancies V G and oxygen substituted at nitrogen sites.The magnetic interaction in Mn-doped GaN favours the ferromagnetic coupling via the double exchange mechanism.The ground state is found to be well described by a model based on a Mn 3+-d 5 in a high spin state coupled via a double exchange to a partially delocalized hole accommodated in the 2p states of neighbouring nitrogen ions.The effect of defects on ferromagnetic coupling is investigated.It is found that in the presence of donor defects,such as oxygen substituted at nitrogen sites,nitrogen vacancy antiferromagnetic interactions appear,while in the case of Ga vacancies,the interactions remain ferromagnetic;in the case of acceptor defects like Mg and Zn codoping,ferromagnetism is stabilized.The formation energies of these defects are computed.Furthermore,the half-metallic behaviours appear in some studied compounds.    

16.  First-Principles Study on Magnetic Properties of V-Doped ZnO Nanotubes  
   张富春  张志勇  张威虎  闫军峰  贠江妮《中国物理快报》,2009年第26卷第1期
   Electronic and magnetic properties of V-doped ZnO nanotubes in which one of Zn^2+ ions is substituted by V^2+ ions are studied by the first-principles calculations of plane wave ultra-soft pseudo-potential technology based on the spin-density function theory. The computational results reveal that spontaneous magnetization in Vdoped (9,0) ZnO nanotubes can be induced without p-type or n-type doping treatment, and the ferromagnetism is isotropic and independent of the chirality and diameter of the nanotubes. It is found that V-doped ZnO nanotubes have large magnetic moments and are ferromagnetic half-metal materials. Moreover, the ferromagnetic coupling among V atoms is generated by O 2p electron spins and V 3d electron spins localized at the exchanging interactions between magnetic transitional metal (TM) impurities. The appearance of ferromagnetism in V-doped ZnO nanotubes gives some reference to fabrication of a transparent ferromagnet which may have a great impact on industrial applications in magneto-optical devices.    

17.  A first-principles study of the magnetic properties in boron-doped ZnO  
   徐晓光  杨海龄  吴勇  张德林  姜勇《中国物理 B》,2012年第21卷第4期
   First-principles calculations based on density functional theory are performed to study the origin of ferromagnetism in boron-doped ZnO. It is found that boron atoms tend to reside at Zn sites. The induced Zn vacancy is a key factor for ferromagnetism in Zn1-xBxO (0    

18.  Electron transfer reaction of meso-phenyl-tetrabenzo-porphyrinato-zinc and dicyanobenzene at low temperature  
   王夺元  胡敏学  胡凌志  赵理曾  卢振中  聂玉昕《中国科学B辑(英文版)》,1997年第40卷第2期
   The behavior of photon-gated spectral hole burning with meso-phenyl-tetrabenzoporphyrinato-zinc as electron donor and dicyanobenzene as electron acceptor dispersed in polymethylmethacrylate was investigated.The data of absorption spectrum of the photoproduct acquired through photon-gated hole burning process by high power density and long hole burning time at 20 K were given The mechanism of photomduced donor-acceptor electron transfer for the iarget system in photon-gated spectral hole burning was demonstrated.    

19.  Effect of the stoichiometry on the electronic structure of the Ni(111)/α-Al2O3(0001) interface: a first-principles investigation  
   施思齐  田中真悟  香山正憲《中国物理 B》,2008年第17卷第7期
   In this paper first-principles calculations of Ni(111)/α-Al2O3(0001) interfaces have been performed, and are compared with the preceding results of the Cu (111)/α-Al2O3(0001) interface [2004 Phil. Mag. Left. 84 425]. The AI- terminated and O-terminated interfaces have quite different adhesion mechanisms, which are similar to the Cu(111)/α Al2O3(0001) interface. For the O-terminated interface, the adhesion is caused by the strong O-2p/Ni-3d orbital hybridization and ionic interactions. On the other hand, the adhesion nature of the Al-terminated interface is the image-like electrostatic and Ni-Al hybridization interactions, the latter is substantial and cannot be neglected. Charge transfer occurs from Al2O3 to Ni, which is opposite to that in the O=terminated interface. The charge transfer direction for the Al-terminated and O-terminated Ni(111)/α-A1203(0001) interfaces is similar to that in the corresponding Cu(111)/α- Al2O3(0001) interface, but there exist the larger charge transfer quantity and consequent stronger adhesion nature, respectively.    

20.  Polarization Induced High A1 Composition A1GaN p-n Junction Grown on Silicon Substrates  
   张鹏  李世彬  余宏萍  吴志明  陈志  蒋亚东《中国物理快报》,2014年第11期
   Wide bandgap Alx Ga1-x N (x = 0.7-1) p-n junction is realized on a silicon substrate through polarization induced doping. Polarization induced positive charge field is produced by linearly grading from A1N to Al0.7Ga0.3N, and negative charge field is generated by an inverted grading from A10.7Ga0.3N to A1N. The polarization charge field induced hole density is on the order of 10^18 cm^-3 in the graded AIxGaI-xN:Be (x = 0.7-1) p-n junction. Polarization doping provides a feasible way to mass produce lll-nitride devices on silicon substrates.    

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