Single-Parameter Quantum Pumping in Graphene Nanoribbons with Staggered Sublattice Potential

We present a theoretical study of quantum charge pumping in metallic armchair graphene nanoribbons using the Floquet Green function method. A central part of the ribbon acting as the scattering region is supposed to have staggered sublattiee potential to open a finite band gap. A single ae gate is asymmetrically applied to a part of the scattering region to drive the pumping. Corresponding to the gap edges, there are two pumped current peaks with opposite current directions, which can be reversed by changing the position of the ac gate relative to the scattering region. The effects of the parameters, such as the staggered sublattice potential, the driving frequency and the geometric parameters of the structure, on the pumping are discussed.

Light-modulated graphene-based φ_(0) Josephson junction and -φ_(0) to φ_(0) transition

We investigate the chiral edge states-induced Josephson current–phase relation in a graphene-based Josephson junction modulated by the off-resonant circularly polarized light and the staggered sublattice potential.By solving the Bogoliubov–de Gennes equation,a φ_(0) Josephson junction is induced in the coaction of the off-resonant circularly polarized light and the staggered sublattice potential,which arises from the fact that the center of-mass wave vector of Cooper pair becomes finite and the opposite center of-mass wave vector to compensate is lacking in the nonsuperconducting region.Interestingly,when the direction of polarization of light is changed,-φ_(0) to φ_(0) transition generates,which generalizes the concept of traditional 0–πtransition.Our findings provide a purely optical way to manipulate a phase-controllable Josephson device and guidelines for future experiments to confirm the presence of graphene-based φ_(0)Josephson junction.

On the Lattice of Convex Sublattices of a Lattice

1 Introduction Let L be a lattice and CS(L) be the family of all convex sublattices of L, includingthe empty set.Then CS(L), partially ordered by inclusion, forms an atomic algebraic lat-tice. K. M. Koh investigated some basic concepts and results of CS(L), and raised the following Problem.

Two-Sublattice Thermodynamic Model on Carbonitride Precipitation in Microalloyed Steels Bearing Nb-V-Ti

Based on the two sublattice model of the regular solution,one being metal atom sublattice and another being interstitial atom sublattice,a thermodynamic model for the precipitates of niobium carbonitride,vanadium carbonitride and titanium carbonitride was established to study the starting-temperature of precipitates and the austenite compositions at given temperature in a low carbon steel.The calculation results show that starting-temperature of the precipitation of niobium carbonitride,vanadium carbonitride and titanium carbonitride are 1100℃,920℃ and 1340℃,respectively,the mole fraction of carbonitride precipitates is 8.65×10-4 in the 0.053C-0.0028N-1.28Mn-0.008S-0.031Al-0.046Nb-0.008Ti0.029V-Fe steel.When the N content is from 0.0028% to 0.0056%,the starting-temperature of the precipitation of the titanium carbonitride changes from 1340℃ to 1430℃.And the C content is from 0.053% to 0.07%,the startingtemperature of the precipitation of the titanium carbonitride hardly changes,but the atomic fraction of niobium in the carbonitride obviously increases.

Luminescence and Energy Transfer of Gd_xY_（1－x）P_5O_（14）：Ce，Tb──I．Preparation，Structure and Spectral Properties

Preparation, structure and spectral properties of rare earth pentaphosphates Gd_xY_(1-x)P_5O_(14): Ce, Tb have been investigated. When x>0. 7, the pentaphosphates belong to monoclinic crystal system Ⅰ with space group P2_1/c (C). When x≤0. 7. they belong to monoclinic crystal system Ⅱ with C2/c (C). The fluorescent and excitation spectra of Gdp_5O_(14), GdP_5O_(14): Ce. GdP_5O_(14) : Tb and Gd_xY_(1-x)P_5O_(14) : Ce, Tb have been studied and the energy transfer phenomenon from Ce(3+)→Gd(3+)→Tb(3+) by the medium of Gd(3+) sublattice has been determined.

Mean-Field Solution of the Mixed Spin-2 and Spin-5/2 Ising Ferrimagnetic System with Different Single-Ion Anisotropies

The mixed spin-2 and spin-5/2 Ising ferrimagnetic system with different anisotropies (DA/z|J|) for the spin-2 and (DB/z|J|) for the spin-5/2 is studied by the use of the mean-field theory based on the Bogoliubov inequality for the free energy. First, the ground state phase diagram of the system at zero temperature is obtained on the (DA/z|J|,DB/z|J|) plane. Topologically, different kinds of phase diagrams are achieved by changing the temperature and the values of the single ion anisotropies DA/z|J| and DB/z|J|. Besides second-order transition lines, first order phase transition lines terminating at tricritical points, are found. The existence and dependence of a compensation temperature on single-ion anisotropies is also investigated.

Luminescence and Energy Transfer of Gd_xY_（1－x）P_5O_（14）：Ce， Tb──Ⅱ． Energy Transfer of Ce→Gd→Tb

The energy transfer phenomenon of Ce→Gd→Tb via Gd sublattice and its depandence has been investigated in GdxY-1-xP5O14:Ce,Tb.The fluorescent and excitation spectra of Gdp5O14,Gdp5O14:Ce,Gdp5O14:Tb and GdxY-1xP5O14:Ce,Tb and absorption spectrum of Gdp5O14 have been studied.The results show that as x is larger than 0.7.the energy transfer from Ce3+ via Gd3+to Tb3+ is obvious.The main reason for the energy transfer of Ce→Gd→Tb being efficient in the region x>0.7 is that the spectral overlap between Ce3+ emission spectrum and Gd3+ absorption spectrum increases and the structure changes from monoclinic Ⅱ(C2/c) layer structure(x<0.7) to monoclinic I(P21/c) ribbon structure.

DIRECT PRODUCT DECOMPOSITION OF MOLECULAR LATTICES AND STRUCTURE OF GENERALIZED ORDER HOMOMORPHISMS

In this note, we shall give the direct product decomposition of a molecular lattice using the concepts of molecules, then we shall discuss the structure of a generalized order homomorphism. About the concepts and notations in this note, refer to [1—7]. L(M) denotes a molecular lattice (i. e. a completely distributive lattice) with M as the set of molecules in L. Let {L_i:i∈I} be a family of mo-

RELATIVELY COMPLEMENTED DISTRIBUTIVE LATTICE

In this paper, we have proved that for a relatively complemented distributive lattice L,there exists one and only one completion ? of L such that for every ξ∈?, there exists afamily {Sα}α∈△ of non-vacuous subsets of L satisfying ξ= ∨[∧f（Sα）]. Such a completion? is called the entire completion of L. We have in this paper extended the homomorphic extension theorem of a generalizedBoolean lattice to that of a relatively complemented distributive lattice and proved that the lat-tice of the congruences on a relatively complemented distributive lattice is isomorphicwith the lattice of the convex sublattices containing a fixed element and that the entire comple-tion of a relatively complemented distributive lattice L, the lattice of the completable con-gruences on L and the lattice of the completable convex sublattices of L containing a fixed ele-ment are isomorphic.

Magneto-electric behaviors of La_(0.67-x)Nd_(x)Sr_(0.33)MnO_(3) system

The polycrystalline samples La_(0.67-x)Nd_(x)Sr_(0.33)MnO_(3)(x=0.1,0.2,0.3,0.4,0.5)were prepared by standard solid-state reaction method,and the M–T curves,electron spin resonance(ESR)curves,infrared spectra,Raman spectra,ρ–T curves and MR–T curves of the compounds above were measured.The results show that single phase can be obtained at different Nd substitution ratios,and with the increase in Nd doping,the magnetic structure of the system transforms from long-range ferro-magnetic order to spin cluster glass state and antiferro-magnetic state;and the phase separation appears in the samples with x=0.3 and 0.4.The transport property exhibits variation with the increase in Nd doping,and the electric behavior of the sample transforms(from metal state to insulator–metal transition,and then insulator state)is accompanied by colossal magnetoresistance(CMR)effect,which can be attributed to the different couplings of sublattices induced by Nd doping and the interface tun-neling effect related to the spin.

Spectrum of L-fuzzy Prime Ideals of a Distributive Lattice

A topological space denoted by Fspec(D),called L-fuzzy prime spectrum of a bounded distributive lattice D is introduced.This space Fspec(D) is compact and it contains a subspace homeomorphic with the prime spectrum of D which is dense in it.The correspondence associating D to the topological space Fspec(D) is shown to define a contravarient functor from the category of bounded distributive lattices into the category of compact topological spaces.