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Lead free relaxor ferroelectrics have attracted continuing interest due to their outstanding and eco-friendly properties. In this paper, dielectric relaxation behavior of the 0.6BaTiO3-0.4Bi(Mg1/2Ti1/2)O3 ceramic (BT-40BMT), which is a typical lead free relaxor ferroelectric, is theoretically and experimentally investigated. At first, the observed dielectric relaxation was quantitatively characterized by a statistical model, indicating that the minority co-related polar nano regions (PNRs) dominate the total polarization. Kinetics of the PNRs were subsequently studied by micro-Raman measurements performed at various temperatures. Here, the relaxation of written domains formed by the piezoresponse force microscopy (PFM) tip-bias induced electric field was also studied, which describes the polarization retention performance of BT-40BMT. The absence of ferroelectric signal contribution in local switching was also confirmed by the contact mode Kelvin PFM technique, indicating the lack of local ferroelectricity. Moreover, the temperature insensitive energy storage property from 293K to 443K was obtained. High voltage pulsed discharge behavior was also investigated by using the pulsed current. A power density of 7.9 x 108W/kg is obtained under a pulsed voltage of 50 kV. Combined with the fast discharge time, the 0.6BaTiO3-0.4Bi(Mg1/2Ti1/2)O3 ceramic is considered as a candidate material for high voltage pulse power applications. [ABSTRACT FROM AUTHOR]

This work presents an examination and unification of fragmented data on spin polarization in half-metallic, ferrimagnetic oxides. It also includes well understood ferromagnetic metals for comparison. The temperature and disorder dependencies of the spin polarization are evaluated. Both the temperature dependence of the tunnel magnetoresistance and, for the very first time, its temperature coefficient are calculated based on the simplified Julliére model. The tunnel magnetoresistance in the magnetic tunnel junctions deteriorates due to the temperature dependence of the spin polarization the lower the Curie temperature is. As a result, magnetic tunnel junctions—consisting of ferromagnetic oxides with a Curie temperature not far above room temperature—are not promising for room temperature applications. Additionally, ferrimagnetic oxides possessing a Curie temperature below 650 K are not suitable for room temperature applications because of an unacceptable temperature coefficient exceeding −2%. [ABSTRACT FROM AUTHOR]

The formation of MCs+ secondary ions in SIMS operated with Cs+ ion beams is discussed on the basis of a well‐confirmed quadratic dependence of MCs+ yields on the atomic polarizabilities of elements M contained in semiconductor samples. This behavior is understood by the generation of a dipole induced in M by the positive charge of a neighboring Cs+ projectile and the mutual induction of a dipole in Cs+, both dipoles depending on the atomic polarizability of M. An evaluation of the dipole–dipole interaction energy indicates that MCs+ ions generated at the target are emitted according to the direct emission model (DEM). This mechanism is in contrast with an association model where constituents of MCs+ are assumed to combine after their independent sputter emission. [ABSTRACT FROM AUTHOR]

The spin momentum non-orthogonality in 3D topological insulators leads to modification of the spin texture and brings in an out-of-plane spin polarization component. Apart from the spin texture, the anomalous thermoelectric properties of these materials are worth studying. In this paper, we have pointed out that the off resonant light used to irradiate the surface states, induces a gap, which becomes momentum dependent due to the presence of non-orthogonal terms in the Hamiltonian. Importantly, to maintain the off resonant condition of light, the momentum value should satisfy a bound. Furthermore, the momentum dependent gap causes a topological transition at a higher value of momentum, which is important to analyse the unusual double peak structure of the Nernst and electrical conductivities. [ABSTRACT FROM AUTHOR]

The established spin splitting in a monolayer (ML) of transition metal dichalcogenides (TMDs) induced by inversion symmetry breaking is dictated by mirror symmetry operations to exhibit the fully out-of-plane direction of spin polarization. Through first-principles density functional theory calculations, we show that polarity inducing mirror symmetry breaking leads to sizable spin splitting having in-plane spin polarization. These splittings are effectively controlled by tuning the polarity using biaxial strain. Furthermore, admixtures between the out-of-plane and in-plane spin-polarized states in the strained polar systems are identified, which are expected to influence the spin relaxation through the Dyakonov–Perel mechanism. Our study clarified that polarity plays an important role in controlling the spin splitting and spin relaxation in the TMD ML, which is useful for designing future spintronic devices. [ABSTRACT FROM AUTHOR]

The inclusion of atomic polarizations for describing molecular electronic structure changes on vibration is shown to be necessary for coherent infrared intensity modeling. Atomic charges from the ChelpG partition scheme and atomic charges and dipoles from Quantum Theory of Atoms in Molecules (QTAIM) were employed within two different models to describe the stretching and bending vibrational intensities of the C-H, C-F, and C=O groups. The model employing the QTAIM parameters was the Charge-Charge Transfer and Dipolar Polarization model (QTAIM/CCTDP), and the model employing the ChelpG charges was the Equilibrium Charge-Charge Flux (ChelpG/ECCF). The QTAIM/CCTDP models result in characteristic proportions of the charge-charge transfer- dipolar polarization contributions even though their sums giving the total intensities do not discriminate between these vibrations. According to the QTAIM/CCTDP model, the carbon monoxide intensity has electronic structure changes similar to those of the carbonyl stretches whereas they resemble those of the CH stretches for the ChelpG/ECCF model. [ABSTRACT FROM AUTHOR]

A key element in the density functional embedding theory (DFET) is the embedding potential. We discuss two major issues related to the embedding potential: (1) its non-uniqueness and (2) the numerical difficulty for solving for it, especially for the spin-polarized systems. To resolve the first issue, we extend DFET to finite temperature: all quantities, such as the subsystem densities and the total system's density, are calculated at a finite temperature. This is a physical extension since materials work at finite temperatures. We show that the embedding potential is strictly unique at T > 0. To resolve the second issue, we introduce an efficient iterative embedding potential solver. We discuss how to relax the magnetic moments in subsystems and how to equilibrate the chemical potentials across subsystems. The solver is robust and efficient for several non-trivial examples, in all of which good quality spin-polarized embedding potentials were obtained. We also demonstrate the solver on an extended periodic system: iron body-centered cubic (110) surface, which is related to the modeling of the heterogeneous catalysis involving iron, such as the Fischer-Tropsch and the Haber processes. This work would make it efficient and accurate to perform embedding simulations of some challenging material problems, such as the heterogeneous catalysis and the defects of complicated spin configurations in electronic materials. [ABSTRACT FROM AUTHOR]

We study ballistic transport of Dirac fermions through silicene barriers, of width d, with an exchange field M and metallic gates above them that provide tunable potentials of height U. Away from the Dirac point (DP), the spin- and valley-resolved conductances, as functions of U, exhibit resonances and close to it a pronounced dip that becomes a transport gap when an appropriate electric field Ez is applied. The charge conductance gc of such a junction changes from oscillatory to a monotonically decreasing function of d beyond a critical Ez. This change of gc can be used to realize electric-field-controlled switching. The field M splits each resonance of gc in two spin-resolved peaks. The spin ps and valley pv polarizations of the current near the DP increase with Ez or M and become nearly perfect above certain of their values. We also show that ps and pv can be inverted either by reversing the polarity of U or the direction of M. For two barriers, there is no splitting in gc when the fields M are in opposite directions. Most of these phenomena have no analogs in graphene. [ABSTRACT FROM AUTHOR]

Chemically synthesized graphene contains large number of defects which act as localized spin moments at the defect sites. Cobalt nanosheets of variable thickness are grown on graphene surface to investigate spin/magnetotransport through graphene sheets containing large number of localized spins. Negative magnetoresistance (MR) is observed over the entire temperature range (5-300 K) for thin cobalt sheets, while a cross-over from negative to positive MR with increasing temperature is noticed for thicker cobalt sheets. The observed MR results are explained on the basis of recently reported spin polarization effect in graphene due to the presence of ferromagnetic atoms on the surface considering a spin valve like Co/graphene/Co nanostructures. [ABSTRACT FROM AUTHOR]

We report the structure, magnetic property, and spin polarization of CoFeMnGe equiatomic quaternary Heusler alloy. The alloy was found to crystallize in the cubic Heusler structure (prototype LiMgPdSn) with considerable amount of DO3 disorder. Thermal analysis result indicated the Curie temperature is about 750K without any other phase transformation up to melting temperature. The magnetization value was close to that predicted by the Slater-Pauling curve. Current spin polarization of P=0.70±0.01 was deduced using point contact andreev reflection measurements. The temperature dependence of electrical resistivity has been fitted in the temperature range of 5-300K in order to check for the half metallic behavior. Considering the high spin polarization and Curie temperature, this material appears to be promising for spintronic applications. [ABSTRACT FROM AUTHOR]

We study the spin-dependent electron transport through a double-stranded DNA (dsDNA) using the Bogoliubov-de Gennes equations and non-equilibrium Green's function method. We calculate the spin-dependent electron conductance and spin-polarization for different lengths, helix angles, twist angles of dsDNA, the environment-induced dephasing factors, and hopping integral. It is shown that the conductance decreases by increasing the length and dephasing factor. Also, we show that the spin-polarization depends on the helical symmetry and the length of DNA. It is shown that the double-stranded DNA can act as a perfect spin filter. Finally, we show that the sign of spin polarization can be inverted from +1 (-1) to -1 (+1) for some values of hopping integral. [ABSTRACT FROM AUTHOR]

The geometric and spin-resolved electronic structure of a graphene-adsorbed Ni(111) surface has been investigated by density functional theory (DFT) calculations without and with a semiempirical long-range dispersion correction (DFT-D). DFT calculations with generalized gradient approximation (GGA) functional cannot predict well about the adsorption properties of graphene to the Ni(111) surface. While DFT-D calculations with the same GGA functional give reasonable values of the adsorption energy and layer distance from graphene to the substrate. The geometry of top_fcc is the most energetically favorable in all geometries. Strong hybridization of graphene with the ferromagnetic Ni substrate induces significant shift partially in graphene π states towards the Fermi level yielding spin polarization. The spin polarization is positive at the shallow levels of modified π states and slightly negative at the deeper levels of fundamental π states, which is indicated by the calculated spin density distributions and plane-averaged density of states at the vacuum side. The opposite spin polarization is consistent with our experimental result of spin asymmetry obtained by spin-polarized metastable-atom de-excitation spectroscopy measurements. [ABSTRACT FROM AUTHOR]

Functionalization of MoS2 sheet (monolayer and bilayer) by the adsorption of transition metal Fe adatom to its surface and interlayer has been investigated computationally using first-principles calculations based on the density functional theory. We found that the systems with absorption of Fe adatoms on the surfaces of both monolayer and bilayer MoS2 sheets are still semiconductors, without spin polarization at the Fermi level. However, for the system with absorption of Fe adatom in the interlayer of bilayer MoS2 sheet, its electronic structure exhibits half-metal behavior, with 100% spin polarization at the Femi level, which provides a promising material for spintronic devices. [ABSTRACT FROM AUTHOR]

A method of coherent controlling the polarization of a medium has been proposed recently for the generation of extremely short pulses. The method is based on the excitation of atomic polarization oscillations and their subsequent stop using a pair of ultrashort pulses. The so-called stopped pulse of the polarization of a medium, which arises in the interval between its excitation and deexcitation, can be a source of an extremely short radiation pulse. In this work, the above-indicated possibility of generation of an isolated attosecond ultraviolet pulse in a three-level resonant medium whose parameters correspond to a hydrogen atom excited by a pair of unipolar X-ray pulses is considered theoretically. In this case, the generation mechanism is of the antenna-type, that is, it is caused by the collective spontaneous emission of pre-phased atoms in the absence of a noticeable decay of their free polarization. [ABSTRACT FROM AUTHOR]

Distribution of the atomic polarization in a Cesium vapor cell, induced by optical pumping, is analytically calculated and discussed when an external magnetic field interacts with the system. Based on the rate equations of the optically pumped atomic system and considering the effect of magnetically induced dichroism on the absorption of polarized propagating light, we have obtained the light intensity and atomic polarization distribution along the propagation direction of the gas cell. It is shown that based on the initial light polarization and the laser detuning, the external magnetic field considerably changes the polarization distribution. The obtained results of the polarization distribution versus applied magnetic field can be used for different investigations, including the study of the atomic magnetometer's sensitivity. [ABSTRACT FROM AUTHOR]

Magnetic tunnel junctions (MTJs) were fabricated with a thin layer of semimetallic bismuth inserted between the tunnel barrier and the top ferromagnetic electrode. The tunneling magnetoresistance (TMR) was measured on a set of samples for which the thickness of the inserted layer varied from 0 to 20 nm. The TMR decreased with an exponential decay length that was found to be λBi =4.1 nm=0.48 λF,Bi, where λF,Bi is the Fermi wavelength measured in comparable Bi films. This result is in remarkably good agreement with the decay length previously measured in MTJs with inserted copper layers, λCu=0.58 λF,Cu, even though the values of λF differ by an order of magnitude. It thereby gives a confirmation that the characteristic length scale of the tunneling density of states is the Fermi wavelength. Measurements of TMR as a function of bias voltage show a large asymmetry and the peak TMR is shifted to a nonzero value. [ABSTRACT FROM AUTHOR]

First principle calculations using supercell approach and coherent potential approximation (CPA) are performed to investigate the electronic and magnetic structures of Fe3-xMnxSi and Fe3-yMnySiy alloys, where x, y=0, 0.25, 0.50, 0.75, 1.00, 1.25, 1.5, 1.75, and 2.25. Using supercell calculations we obtained a metallic behavior for x=0, 0.25, and 0.5 in Fe3-xMnxSi alloys with spin polarizations of 24%, 39%, and 93%, respectively. The behavior starts to be half-metallic at x=0.75 with a small direct band gap that increases for higher concentrations of Mn. Among the half-metallic systems, only those of L21 structure at x=1 and 2 possess indirect band gaps along Γ-X symmetry line. The change of Si concentration in Fe3-yMnySiy structures retrieve the metallic behavior for all concentrations except y=1.25 that shows a half-metallic behavior with a direct band gap of 0.27 eV. We obtained a good agreement between supercell and CPA calculations for the values of the magnetic moment and the trends of the formation energies, which reveals the validity of the supercell approach in predicting the magnetic structure and the energetics of doped Heusler alloys. [ABSTRACT FROM AUTHOR]

Recent advances in scanning probe techniques rely on the chemical functionalization of the probe-tip termination by a single molecule. The success of this approach opens the prospect of introducing spin sensitivity through functionalization by a magnetic molecule. We used a nickelocene-terminated tip (Nc-tip), which offered the possibility of producing spin excitations on the tip apex of a scanning tunneling microscope (STM). When the Nc-tip was 100 picometers away from point contact with a surface-supported object, magnetic effects could be probed through changes in the spin excitation spectrum of nickelocene. We used this detection scheme to simultaneously determine the exchange field and the spin polarization of iron atoms and cobalt films on a copper surface with atomic-scale resolution. [ABSTRACT FROM AUTHOR]

Abstract The structural, mechanical, electronic and magnetic properties of quaternary Heusler ZrTiRhGa alloy have been investigated by using the first-principles calculations within the generalized gradient approximation GGA. The results of our calculations show that the type (I) of ZrTiRhGa, with the ferromagnetic (FM) state, is the most stable configuration among three possible configurations. The GGA + U calculations, where U is on-site Coulomb interaction correction, are performed to investigate the relationship between band gap and Hubbard potential. The calculated results showed that ZrTiRhGa compound is half-metallic material (HMM) with complete spin polarization around the Fermi level. The total magnetic moment is 2 μB per formula unit and follows the Slater-Pauling rule μt = Zt−18. The calculated elastic constants, cohesive and formation energy, for ZrTiRhGa compound, were analyzed in detail and reveal the mechanical stability. In addition, we investigated the sensitivity of the half-metallicity with two structural-type changes: hydrostatic and tetragonal deformation. Our calculations show that the half-metallicity can be preserved with lattice constants from 5.74 Å to 7.12 Å, under the influence of hydrostatic strain and in the range of the c/a ratio from −8% to 12% with the effect of the tetragonal strain. For ZrTiRhGa, since there is no available experimental data, our calculations are considered as first predictions. Highlights • The quaternary Heusler ZrTiRhGa alloy has HM nature at the equilibrium volume. • The calculated Mtot of quaternary Heusler ZrTiRhGa alloy is 2 µB, which is in agreement with Slater- Pauling rule. • ZrTiRhGa alloy maintains the HM nature when the values of lattice constant are included between 5.74 Ǻ -7.12 Ǻ. • The quaternary Heusler ZrTiRhGa alloy maintains the HM nature, in the range of the c/a ratio from 0.81 to 1.2. [ABSTRACT FROM AUTHOR]

To clarify the origins of different magnetic behavior in ferromagnetic LaCo2P2 and antiferromagnetic RCo2P2 (R=Ce, Pr, Nd, and Sm), quaternary phases La0.9R0.1Co2P2 have been investigated. While LaCo2P2 orders ferromagnetically at 132 K, the introduction of the small amount of R into the La sublattice increases the ferromagnetic ordering temperature, which correlates with the size of the R3+ ion (TC=144 K, 150 K, 161 K, and 165 K for Ce, Pr, Nd, and Sm, respectively). This change is attributed to the increasing Co-Co separation within the [Co2P2] layer, which results in higher spin polarization of the Co 3d subband. The low-temperature magnetism of La0.9R0.1Co2P2 strongly depends on the nature of the rare-earth metal. [ABSTRACT FROM AUTHOR]

Relationship between FeCo crystalline orientation and magnetic properties of TbFeCo/FeCo/Ta trilayer films was investigated. FeCo crystalline orientation could be controlled by changing FeCo deposition rate. Ferromagnetic Hall effect observation clarified that perpendicular component of magnetization in FeCo layer of TbFeCo/FeCo(001)/Ta were better than that of TbFeCo/FeCo(110)/ Ta. Lattice spacing of both FeCo(001) films and FeCo(110) ones in the TbFeCo(50 nm)/FeCo (X nm) was also observed. Expansion ratios of FeCo(001) toward film normal direction were higher than that of FeCo(110) as increasing FeCo film thickness, and this indicated that FeCo(001) films were more favorable for magnetic coupling with rare-earth transition metal (RE-TM) alloy films than FeCo(110) ones when FeCo films become thick. However investigation of relationship between FeCo expansion ratios and magnetic properties of TbFeCo/FeCo(001) or (110) (X nm)/Ta trilayer films showed that squareness ratios of specimens with FeCo(001) were worse than that with FeCo(110). [ABSTRACT FROM AUTHOR]

It is a truth universally acknowledged that a Heusler compound in possession of a good order must be in want of a high spin polarization. In the present work, we investigated the spin polarization of the Heusler compound Co2FeAl by spin polarized tunneling through a MgO barrier into a superconducting Al-Si electrode. The measured spin polarization of P=55% is in good agreement with the previously obtained tunnel magnetoresistance values and compared to the data by other groups. [ABSTRACT FROM AUTHOR]

Highlights • A spin current generator in a single molecular magnet is realized. • The spin-related currents are studied by Hubbard operator Green’s function method. • The system can generate spin-polarized current or pure spin current. • Two configurations of spin bias are considered and they show different features. Abstract In this paper we study the spin- and charge-transport behaviors of a single molecular magnet (SMM) coupled to external reservoirs with spin-dependent chemical potentials. By using the Hubbard operator Green’s function method, we show that in the limit of a pinned macrospin the SMM can serve as an effective spin current filter or generator. Two configurations of spin bias are considered. For SMM coupled with symmetric dipolar spin bias, the system can generate spin-polarized current and pure spin current by adjusting the relative magnitude of spin bias and Coulomb interaction. It originates from the competition of two spin-opposite transport channels. Also due to this competition, one can observe a negative differential spin conductance. For SMM coupled with asymmetric dipolar spin bias, the system can only generate spin-polarized currents. The SMM as a spin current generator shows features different from the usual quantum dot system and these features can be useful in molecular spintronics. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Atomic magnetometer array demonstrates interference rejection by factor of 120–250. • Phase-encoded reference signal used for real-time correction of unshielded signals. • Reference calibration depends on 87 Rb polarization, RF pulse duration & direction. • RF pulses orthogonal to pump and probe beams provide robust ESR calibration. Abstract An unshielded array of 87 Rb atomic magnetometers, operating close to 1 MHz, is used to attenuate interference by 42–48 dB. A sensitivity of 15 fT / Hz to a local source of signal is retained. In addition, a 2D spectroscopic technique, in which the magnetometers are repeatedly pumped and data acquired between pump times, enables a synchronously generated signal to be distinguished from an interfering signal very close in frequency; the timing and signal mimics what would be observed in a magnetic resonance echo train. Combining the interference rejection and the 2D spectroscopy techniques, a 100 fT local signal is differentiated from a 20 pT interference signal operating only 1 Hz away. A phase-encoded reference signal is used to calibrate the magnetometers in real time in the presence of interference. Key to the strong interference rejection is the accurate calibration of the reference signal across the array, obtained through electron spin resonance measurements. This calibration is found to be sensitive to atomic polarization, RF pulse duration, and direction of the excitation. The experimental parameters required for an accurate and robust calibration are discussed. [ABSTRACT FROM AUTHOR]

A polarizable atomic multipole-based force field for the membrane bilayer models 1,2-dioleoyl-phosphocholine (DOPC) and 1-palmitoyl-2-oleoyl-phosphatidylethanolamine (POPE) has been developed. The force field adopts the same framework as the Atomic Multipole Optimized Energetics for Biomolecular Applications (AMOEBA) model, in which the charge distribution of each atom is represented by the permanent atomic monopole, dipole and quadrupole moments. Many-body polarization including the inter- and intra-molecular polarization is modelled in a consistent manner with distributed atomic polarizabilities. The van der Waals parameters were first transferred from existing AMOEBA parameters for small organic molecules and then optimised by fitting to ab initio intermolecular interaction energies between models and a water molecule. Molecular dynamics simulations of the two aqueous DOPC and POPE membrane bilayer systems, consisting of 72 model molecules, were then carried out to validate the force field parameters. Membrane width, area per lipid, volume per lipid, deuterium order parameters, electron density profile, etc. were consistent with experimental values. [ABSTRACT FROM AUTHOR]

We report on magnetism, transport and spin polarization characteristics of the melt-spun Cu 2 MnSn alloy prepared by the rapid quenching technique. The as- cast ribbons showed a relatively well ordered chemical composition (Cu = 50.4%, Mn = 27.1%, Sn = 22.5%). The structural characterization by using X-ray diffraction shows L2 1 /B2 crystalline structure with the lattice parameter a = 6.196 Å. The magnetic and transport measurements show a metallic behavior with the Curie temperature of 530 K and reveal anisotropic character with the easy magnetization plane parallel with respect to the ribbon plane. As-cast Cu 2 MnSn ribbons show the spin polarization measured by using Andreev reflection technique within the range 68–75%. [ABSTRACT FROM AUTHOR]

Within the factorization-assisted topological-amplitude approach, we studied the 33 charmless $$B_{(s)} \rightarrow VV$$ decays, where V stands for a light vector meson. According to the flavor flows, the amplitude of each process can be decomposed into eight different topologies. In contrast to the conventional flavor diagrammatic approach, we further factorize each topological amplitude into decay constant, form factors and unknown universal parameters. By $$\chi ^2$$ fitting 46 experimental observables, we extracted 10 theoretical parameters with $$\chi ^2$$ per degree of freedom around 2. Using the fitted parameters, we calculated the branching fractions, polarization fractions, CP asymmetries and relative phases between polarization amplitudes of each decay mode. The decay channels dominated by tree diagram have large branching fractions and large longitudinal polarization fraction. The branching fractions and longitudinal polarization fractions of color-suppressed decays become smaller. Current experimental data of large transverse polarization fractions in the penguin dominant decay channels can be explained by only one transverse amplitude of penguin annihilation diagram. Our predictions of the not yet measured channels can be tested in the ongoing LHCb experiment and the Belle-II experiment in the future. [ABSTRACT FROM AUTHOR]

The effect of a double structure of saturated absorption resonance in the field of counterpropagating light waves interacting with an atomic gas is studied. The experimental observation of this effect was first reported in 2011 in a work by our colleagues at the P.N. Lebedev Physical Institute of the Russian Academy of Sciences (Laboratory of Frequency Standards). The essence of the effect lies in the fact that, on exciting an open dipole transition, another, narrower, resonance of an opposite sign can be observed at the center of the ordinary saturated absorption resonance. A theoretical analysis of this effect has also been performed in this work in terms of a simple spectroscopic model of an atom with two nondegenerate energy levels without taking into account higher spatial harmonics of atomic polarization and polarizations of light waves (scalar model). The present work is devoted to the development of a theory of the formation of a central narrow resonance for the example of a real F = 1 → F = 1 atomic transition and to the study of its main characteristics (amplitude, width, contrast, and amplitude-to-width ratio). In addition, the theoretical results obtained without taking into account the influence of higher spatial harmonics and with inclusion of the influence of first higher harmonics are compared. This comparison shows that their influence on the parameters of the new nonlinear resonance is strong even in moderately intense light fields ( R ~ γ, where R is the Rabi frequency). The results of this study can be of interest for quantum metrology, as well as for many experiments in which the laser-radiation frequency is stabilized by the saturated absorption resonance on open dipole transitions in atoms and molecules. [ABSTRACT FROM AUTHOR]

Simulations of the generation of the atomic polarization is necessary for interpreting the second solar spectrum. For this purpose, it is important to rigorously determine the effects of the isotropic collisions with neutral hydrogen on the atomic polarization of the neutral atoms, ionized atoms and molecules. Our aim is to treat in generality the problem of depolarizing isotropic collisions between singly ionized atoms and neutral hydrogen in its ground state. Using our numerical code, we computed the collisional depolarization rates of the p -levels of ions for large number of values of the effective principal quantum number n * and the Unsöld energy E p . Then, genetic programming has been utilized to fit the available depolarization rates. As a result, strongly non-linear relationships between the collisional depolarization rates, n * and E p are obtained, and are shown to reproduce the original data with accuracy clearly better than 10%. These relationships allow quick calculations of the depolarizing collisional rates of any simple ion which is very useful for the solar physics community. In addition, the depolarization rates associated to the complex ions and to the hyperfine levels can be easily derived from our results. In this work we have shown that by using powerful numerical approach and our collisional method, general model giving the depolarization of the ions can be obtained to be exploited for solar applications. [ABSTRACT FROM AUTHOR]

Metal–organic networks have become very popular materials in view of various chemical and physico-chemical applications. Much attention is normally focused on porous compounds (metal–organic frameworks), although densely packed polymers may also find applications. In this paper, we propose a rather simplified method to estimate the dielectric constants and the optical indicatrices of metal–organic networks, which could be useful for rapid selection of materials with specific optical properties. The method adopts the distributed atomic polarizabilities calculated for secondary building units of metal–organic networks. With the atomic quantities, one can evaluate the crystal susceptibility, assuming an oriented gas model corrected for the polarization induced by the crystal medium. A simple oriented gas model enables a rapid evaluation of the anisotropy of the optical indicatrix of a crystal, as confirmed by calculations under periodic boundary conditions. The correction for polarization induced by the crystalline environment provides, in addition, more accurate estimation of the refractive indices, at least in the regime of low frequencies. The computational costs are smaller than those for fully periodic calculations and could be significantly smaller if a set of precomputed, transferable atomic polarizabilities would be used. [ABSTRACT FROM AUTHOR]

We investigate the entropy squeezing of a two-level atom coupled to a dissipative cavity under two different controls: In the first case, quantum-jump-based feedback is alone applied, whereas in the second case we consider the combined effect of quantum-jump-based feedback and classical driving, in which we provide a scheme to generate and protect steady and optimal entropy squeezing of the two-level atom. The results show that the entropy squeezing of atomic polarization components greatly depends on the control of quantum-jump-based feedback and classical driving. Under the condition of designing proper quantum-jump-based feedback parameters, the entropy squeezing can be generated and protected. Furthermore, when both quantum-jump-based feedback and classical driving are simultaneously applied, steady and optimal entropy squeezing of the two-level atom can be obtained even though there is initially no entropy squeezing, which is explained by making use of the steady-state solution of the atom. [ABSTRACT FROM AUTHOR]

We evaluate embedding potentials, obtained via various methods, used for polarizable embedding computations of excitation energies of para-nitroaniline in water and organic solvents as well as of the green fluorescent protein. We found that isotropic polarizabilities derived from DFTD3 dispersion coefficients correlate well with those obtained via the LoProp method. We show that these polarizabilities in conjunction with appropriately derived point charges are in good agreement with calculations employing static multipole moments up to quadrupoles and anisotropic polarizabilities for both computed systems. The (partial) use of these easily-accessible parameters drastically reduces the computational effort to obtain accurate embedding potentials especially for proteins. © 2016 The Authors. Journal of Computational Chemistry Published by Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Interface characteristics of Co 2 MnSi/Ag/Co 2 MnSi trilayer have been investigated by means of first-principles. The most likely interface is formed by connecting MnSi-termination to the bridge site between two Ag atoms. As annealed at high temperature, the formation of interface DO 3 disorder is most energetically favorable. The spin polarization is reduced by both the interface itself and interface disorder due to the interface state occurs in the minority-spin gap. As a result, the magneto-resistance ratio has a sharp drop based on the estimation of a simplified modeling. [ABSTRACT FROM AUTHOR]

In this perspective article, we revise some of the empirical and semi-empirical strategies for predicting how hydrogen bonding affects molecular and atomic polarizabilities in aggregates. We use p-nitroaniline and hydrated oxalic acid as working examples to illustrate the enhancement of donor and acceptor functional-group polarizabilities and their anisotropy. This is significant for the evaluation of electrical susceptibilities in crystals; and the properties derived from them like the refractive indices. [ABSTRACT FROM AUTHOR]

ULTRASPIN is an apparatus devoted to the measurement of the spin polarization (SP) of electrons ejected from solid surfaces in a UHV environment. It is designed to exploit ultrafast light sources (free electron laser or laser high harmonic generation) and to perform (photo)electron spin analysis by an arrangement of Mott scattering polarimeters that measure the full SP vector. The system consists of two interconnected UHV vessels: one for surface science sample cleaning treatments, e-beam deposition of ultrathin films, and low energy electron diffraction/AES characterization. The sample environment in the polarimeter allows for cryogenic cooling and in-operando application of electric and magnetic fields. The photoelectrons are collected by an electrostatic accelerator and transport lens that form a periaxial beam that is subsequently directed by a Y-shaped electrostatic deflector to either one of the two orthogonal Mott polarimeters. The apparatus has been designed to operate in the extreme conditions of ultraintense single-X-ray pulses as originated by free electron lasers (up to 1 kHz), but it allows also for the single electron counting mode suitable when using statistical sources such as synchrotron radiation, cw-laser, or e-gun beams (up to 150 kcps). [ABSTRACT FROM AUTHOR]

We have studied a range of polar and nonpolar materials using x-ray absorption near-edge spectroscopy (XANES) in external electric fields. An energy shift of the XANES by a few meV/kV is found which scales linearly with the applied voltage, thus being reminiscent of the linear Stark effect. This is corroborated by the consistent presence of this energy shift in polar thin films and bulk crystals and its absence in nonpolar materials as well as in conducting films. The observed energy shift of the XANES is different between two atomic species in one specimen and appears to scale linearly with the atomic number of the studied element. Therefore, XANES in electrical fields opens the perspective to study atomic polarization with element specificity in a range of functional materials. [ABSTRACT FROM AUTHOR]

The electronic effects operative in a series of cyclophosphazenes with organic substituents N3P3F5R (R = ethynyl, vinyl, allyl, ethyl, styrenyl) were explored using ab initio and density functional calculations followed by natural bond order (NBO) analyses. The effects of organic group on the phosphazene ring and that of phosphazene on the organic center were examined using NBO charges, atomic orbital coefficients, Wiberg bond orders, and orbital populations. The electronic effect of the P3N3F5moiety on an unsaturated carbon center is best described as electron donating from phosphorus to carbon through a polarized σ bond and strong electrostatic polarization of the organic π system toward the C1 carbon atom. [ABSTRACT FROM PUBLISHER]

High order harmonics generated at relativistic intensities have long been recognized as a route to the most powerful extreme ultraviolet pulses. Reliably generating isolated attosecond pulses requires gating to only a single dominant optical cycle, but techniques developed for lower power lasers have not been readily transferable. We present a novel method to temporally gate attosecond pulse trains by combining noncollinear and polarization gating. This scheme uses a split beam configuration which allows pulse gating to be implemented at the high beam fluence typical of multi-TW to PW class laser systems. Scalings for the gate width demonstrate that isolated attosecond pulses are possible even for modest pulse durations achievable for existing and planned future ultrashort high-power laser systems. Experimental results demonstrating the spectral effects of temporal gating on harmonic spectra generated by a relativistic laser plasma interaction are shown. [ABSTRACT FROM AUTHOR]

Solution of a strong electrolyte in a high-density polar fluid gives rise to a dielectric saturation that decreases the orientation polarizability of the solvent molecules in close proximity to the ions wherefore the relative permittivity in this region is determined solely by the atomic and electronic polarization. This causes a substantial decrease in the static permittivity of the solution. By considering the dielectric saturation, a model for the permittivity of an electrolyte solution have been developed and the parameters, the relative permittivities at dielectric saturation in close proximity to the ions, for 17 ions in water at 298.15 K were determined. By scaling these relative permittivities in proportion to the permittivity of the solvent, the model could be extended to calculate the permittivity of solutions of electrolytes in methanol and admixtures of water and ethanol. © 2015 American Institute of Chemical Engineers AIChE J, 61: 2854-2860, 2015 [ABSTRACT FROM AUTHOR]

This paper introduces explicit dependenceof atomic polarizabilitieson intermolecular interactions within the framework of a polarizableforce field AMOEBA. Polarizable models used in biomolecular simulationsoften poorly describe molecular electrostatic induction in condensedphase, in part, due to neglect of a strong dependency of molecularelectronic polarizability on intermolecular interactions at shortdistances. Our variable polarizability model parameters are derivedfrom quantum chemical calculations of small clusters of atoms andmolecules, and can be applied in simulations in condensed phase withoutadditional scaling factors. The variable polarizability model is appliedto simulate a ligand exchange reaction for a Mg2+ion solvatedin water. Explicit dependence of water polarizability on a distancebetween a water oxygen and Mg2+is derived from in vacuumMP2 calculations of Mg2+–water dimer. The simulationsyield a consistent description of the energetics of the Mg2+–water clusters of different size. Simulations also reproducethermodynamics of ion solvation as well as kinetics of a water ligandexchange reaction. In contrast, simulations that used the additiveforce field or that used the constant polarizability models were notable to consistently and quantitatively describe the properties ofthe solvated Mg2+ion. [ABSTRACT FROM AUTHOR]

Atomic Fukui indices have been calculated by integration of the polarization justified Fukui functions over the atomic basins. Resulting indices have been explored in the definition of the atomic and group affinity indicator and softnesses on the ground of the formal analysis of the polarization effect. These indicators combine the effect of the atomic charge and atomic Fukui index. They are potentially applicable in testing a sensing effect on a molecule induced by an approaching point agent, nucleophilic (−) or electrophilic (+), at a distance in the order of v.d. Waals radii. Calculated atomic and group affinity and softness indicators have been proved to be consistent with the well established trends of reactivity for a control group of the five-atom-ring heterocycles (imidazole, oxazole, thiazole). The indices have been applied to the set of 5 nucleobases (adenine, guanine, cytosine, thymine, uracyl), whose diverse reactivity towards electrophiles has been recognized as a key factor determining the sensitivity of DNA to cytotoxic agents. The pairing effect of the nucleobases bases in the DNA chain and the experimental trends of the site reactivity of these molecules have been properly accounted for by the calculated indicators. [ABSTRACT FROM AUTHOR]

Spin dependent transport in one-dimensional (1D) three-terminal rings is investigated in the presence of the Rashba spin-orbit coupling (RSOC). We focus on the spin dependent conductances and the components of the spin polarization vectors of the currents in the outgoing terminals. For this purpose, the transmission coefficients with respect to the σx, σy and σz basis are obtained, and the three components of the spin polarization vectors are evaluated analytically. The total conductances, the spin dependent conductances and the polarization components are obtained as functions of the incident electron energy, as well as the RSOC strength, for the totally symmetric, partially symmetric and asymmetric cases. It is found that the spin polarizations corresponding to the σy basis are zero, and that there is a symmetry in the total conductances, the spin dependent conductances and the polarization components for symmetric cases, i.e., G1 = G2, g1τ = g2-τ, and P1i = -P2i (i = x, z). This symmetry is attributed to the rotational symmetry in the symmetrically coupled rings. For asymmetric cases, however, it is broken by the asymmetric lead-ring configuration. [ABSTRACT FROM AUTHOR]