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The ‘pseudo-Edelstein’ effect by which charge current J x converts to pseudo-spin polarization, τ z , has been investigated theoretically for an infinite sheet of silicene. Calculations have been performed for conductor phase of silicene within the Dirac point approximation and in the presence of normally applied electric field. The latter conversion as an outcome of voltage-texture correlation in buckled silicene has been considered as ‘pseudo-Edelstein’response function. This response function have been calculated in the context of Kubo formalism in the presence of vertex corrections. It has been verified that the charge current results in normal pseudo-spin polarization i.e. sublattice population imbalance. According to obtained results in the presence of vertex corrections, ‘pseudo-Edelstein’ response function is weakened by several orders of magnitude with non-identical different valley contributions. In addition, extra small oscillations of obtained response function have been observed. Nevertheless, when the vertex corrections is off, the ‘pseudo-Edelstein’ response function is strengthened by several orders of magnitudes with the same different valleys contributions and the extra small oscillations of obtained response function are disappeared. These findings show that ‘pseudo-Edelstein’ response function is weakened by the intrinsic Rashba spin–orbit interaction which originally arises from buckling in silicene. As silicene has the lowest buckling among the graphene-like Dirac materials so it can be expected that ‘pseudo-Edelstein’ effect could be realized in a more pronounced manner in silicene. Obviously, this novel type of conversion not only can be employed in the future data transfer technology but also opens a sensible way to control of electrons populations electrically in realistic disordered silicene samples. The optical absorption spectroscopy could be taken as an efficient experimental plan of action by which the results of present work can be checked out.

We propose a technique to design highly-efficient and -unidirectional DFB Raman fiber lasers based on the engineering of the grating’s coupling coefficient including a π-phase shift position in the fiber. For this purpose, first the ideal intra-cavity signal powers for different pump power levels are determined for given fiber lengths. Then, the sum and difference between the counter-propagating wave intensities at each small segment within fiber lengths are calculated resulting in determining the ideal grating’s coupling functions for co- and contra-directional-pumping. The steady-state behavior of the laser using realistic parameters is finally simulated for modified coupling functions considering the Kerr nonlinearity. For a 10 W co-directional-pumped, ∼1 m long single-mode super-efficient DFB, a ∼50% increase in the laser efficiency, more than 44 dB reduction in contra-directional lasing power, ∼15 times drop in the peak power of intra-cavity signal and ∼38% decrease in the unused-pump power are found, compared to those in a standard DFB with the same coupling-length product. Although an enhanced nonlinear refractive index due to thermal gradient reduces the output power of such lasers, it is shown that the super-efficient laser presents a better performance than the standard one, under such conditions.

Atomistic simulations of bicrystal samples containing a grain boundary are used to examine the effect of hydrogen atoms on the nucleation of intergranular cracks in Ni. Specifically, the theoretical strength is obtained by rigid separation of the two crystals above and below the GB and the yield strength (point of dislocation emission) is obtained by standard tension testing normal to the GB. These strengths are computed in pure Ni and Ni with H segregated to the grain boundaries under conditions typical of H embrittlement in Ni, and in artificially highly-H-saturated states. In all GBs studied here, the theoretical strength sigma(y) is not significantly reduced by the presence of the hydrogen atoms. Similarly, with the exception of the Ni Sigma 27(115) boundary, the yield strength sigma(y) is not significantly altered by the presence of segregated H atoms. In all cases, the theoretical strengths are similar to 25 GPa and the yield strengths are similar to 10 GPa, so that (i) the theoretical strength is always well above the yield strength, with or without H, and (ii) both strengths are far above the bulk plastic flow stress, sigma(B)(y) of Ni and Ni alloys. Significant reductions in fracture energy (25%-45%) are only achieved for some of the artificially high-H-segregation cases and then only when all the H around the GB is allow to diffuse locally to the fracture surface, which corresponds to unlikely out-of-equilibrium segregation plus local kinetics. Complementing recent work showing that H does not change the ability of GB cracks to emit dislocations and blunt, the present work indicates that equilibrium segregation of hydrogen atoms to GBs has little effect on lowering the GB strength and energy, and so does not significantly facilitate nucleation of intergranular cracks.

Atomistic simulations of the interactions between dislocations, hydrogen atoms, and vacancies are studied to assess the viability of a recently proposed mechanism for the formation of nanoscale voids in Fe-based steels in the presence of hydrogen. Quantum-mechanics/molecular-mechanics method calculations confirm molecular statics simulations based on embedded atom method (EAM) potential showing that individual vacancies on the compressive side of an edge dislocation can be transported with the dislocation as it glides. Molecular dynamics simulations based on EAM potential then show, however, that vacancy clusters in the glide plane of an approaching dislocation are annihilated or reduced in size by the creation of a double-jog/climb process that is driven by the huge reduction in energy accompanying vacancy annihilation. The effectiveness of annihilation/reduction processes is not reduced by the presence of hydrogen in the vacancy clusters because typical V-H cluster binding energies are much lower than the vacancy formation energy, except at very high hydrogen content in the cluster. Analysis of a range of configurations indicates that hydrogen plays no special role in stabilizing nanovoids against jog formation processes that shrink voids. Experimental observations of nanovoids on the fracture surfaces of steels must be due to as-yet undetermined processes.

This paper provides the first detailed temporal characterization of a multi-wavelength-Brillouin–erbium fiber laser (MWBEFL) by measuring the optical intensity of the individual frequency channels with high temporal resolution. It is found that the power in each channel is highly unstable due to the excitation of several cavity modes for typical conditions of operation. Also provided is the real-time measurements of the MWBEFL output power for two configurations that were previously reported to emit phase-locked picosecond pulse trains, concluded from their autocorrelation measurements. Real-time measurements reveal a high degree of instability without the formation of a stable pulse train. Finally, we model the MWBEFL using coupled wave equations describing the evolution of the Brillouin pump, Stokes and acoustic waves in the presence of stimulated Brillouin scattering, and the optical Kerr effect. A good qualitative consistency between the simulation and experimental results is evident, in which the interference signal at the output shows strong instability as well as the chaotic behavior due to the dynamics of participating pump and Stokes waves.

Cerium-substituted yttrium iron garnet (Ce x Y3−x Fe5O12 or Ce : YIG) thin films with a high Ce content are very hard to achieve because of the solubility limit of Ce in the yttrium iron garnet (YIG) structure. In this work a Ce : YIG target with nominal formula of CeY2Fe5O12 was fabricated by the conventional ceramic method. Phase formation and crystal structure of the samples were investigated by the x-ray diffraction (XRD) method and the results showed that the minimum temperature to get a single phase CeY2Fe5O12 is 1400 °C. CeY2Fe5O12 thin film was deposited on a GGG (4 4 4) single crystal substrate, using the pulsed laser deposition method and its microstructure and magneto-optical (MO) properties were studied. Trying different conditions, a preferred (4 4 4) oriented CeY2Fe5O12 thin film was fabricated under an optimum condition. The results showed that a crystalline CeY2Fe5O12/GGG thin film can be obtained by annealing of the as-deposited film at 600 °C. XRD measurements on the annealed thin film showed that the mean grain size was 38 nm, using Scherrer's formula. Scanning electron microscopy image of the annealed thin film showed that the mean grain size was 35 nm, which is in good agreement with XRD measurements. Atomic force microscopy (AFM) image of the annealed sample showed that the thin film had a smooth surface. Faraday rotation provided by the thin film at wavelength λ = 635 nm was measured to be 2.4° µm−1 in a magnetic field of 600 mT. Transmission spectrum of the thin film was recorded in the visible and near-infrared regions, from 400 to 1000 nm, and it showed good transparency, more than 78%, in the near-infrared region. These measurements resulted in an MO figure of merit of 0.146, which is one of the highest values reported up to now. It is expected that CeY2Fe5O12 thin films could be used as new Faraday rotator materials, applicable in optical isolators and circulators.

We report an experimental study on the effect of magnetic annealing process on the optical and magneto-optical properties of Ce-substituted yttrium iron garnet thin films incorporating gold nanoparticles. Au nanoparticles were formed by heating an Au thin film on a cubic quartz substrate in a vacuum chamber and a Ce : YIG layer was deposited on them by the aid of the pulsed laser deposition method. Our results show that magnetic annealing leads to an increase in nanoparticle sizes and directs the magnetization to lie on the sample's surface. Hence, Faraday rotation signal decreases and a sufficient increase in the longitudinal magneto-optical Kerr effect occurs at different oblique incidence angles. Tuning the surface plasmon resonance band by changing the angle of incidence of the excitation light would add an additional degree of freedom and flexibility to the development of magneto-optical sensors.

We have investigated the behaviour of an engineered one-dimensional magneto-photonic crystal with a (TiO2/SiO2)6/Bi : YIG/(SiO2/TiO2)6 structure for use in wavelength division multiplexing. The magnetic defect layer was fabricated using the pulsed laser deposition technique between two dielectric mirrors. The optical and magneto-optical properties of the sample were studied in detail so as to corroborate, or otherwise, the hypotheses formulated to achieve sufficient Faraday rotation of the media originating in the localized peak of light. Results indicate that this magneto-photonic crystal can be considered as a candidate for a multichannel isolator in wavelength division multiplexing systems. Also, the low-temperature behaviour of this sample indicates five order of magnitude enhancements in the magneto-optical Faraday rotation.

The effect of a pulsed magnetic field on domain wall magnetoresistance for an ideal one-dimensional magnetic nanowire with a domain wall has been investigated. The analysis has been based on the Boltzmann transport equation, within the relaxation time approximation. The results indicate that the domain wall resistance increase when enhancing the magnetic field. The evaluation of local magnetization has been considered in the presence of a pulsed magnetic field. The time evaluation of the magnetization also has an effect on the domain wall resistance. The resistance depends on the contribution of the Zeeman and exchange interactions.