Intra-molecular magnetic exchange interaction in the tripyridinium bis[tetrachloroferrate(iii)] chloride molecular magnet: a broken symmetry-DFT study.

The investigation of magnetic ordering in magnetic molecular conductors is the subject of ongoing research studies in the fields of condensed matter physics, chemistry and material sciences. Following the photo-magnetic behavior already observed in individual (FeCl4)2(py·H)3Cl molecules at room temperature, magnetic ordering is studied in this work. Calculations are performed using spin projected broken symmetry via density functional theory within the scheme of the B3LYP approximation. The value of the intra-molecular magnetic coupling constant is obtained as J = 13.2062 kJ mol(-1). A field dependent magnetization experiment is conducted to validate the magnitude and the sign of the exchange constant. Reasonable consistency of experimental and theoretical results confirms the presence of a positive intra-molecular indirect exchange interaction. This work paves the way for possible introduction of a new molecule in the development of advanced molecular electronic devices.

Magnetic generation of normal pseudo-spin polarization in disordered graphene.

Spin to pseudo-spin conversion by which the non-equilibrium normal sublattice pseudo-spin polarization could be achieved by magnetic field has been proposed in graphene. Calculations have been performed within the Kubo approach for both pure and disordered graphene including vertex corrections of impurities. Results indicate that the normal magnetic field [Formula: see text] produces pseudo-spin polarization in graphene regardless of whether the contribution of vertex corrections has been taken into account or not. This is because of non-vanishing correlation between the [Formula: see text] and [Formula: see text] provided by the co-existence of extrinsic Rashba and intrinsic spin-orbit interactions which combines normal spin and pseudo-spin. For the case of pure graphene, valley-symmetric spin to pseudo-spin response function is obtained. Meanwhile, by taking into account the vertex corrections of impurities the obtained response function is weakened by several orders of magnitude with non-identical contributions of different valleys. This valley-asymmetry originates from the inversion symmetry breaking generated by the scattering matrix. Finally, spin to pseudo-spin conversion in graphene could be realized as a practical technique for both generation and manipulation of normal sublattice pseudo-spin polarization by an accessible magnetic field in a easy way. This novel proposed effect not only offers the opportunity to selective manipulation of carrier densities on different sublattice but also could be employed in data transfer technology. The normal pseudo-spin polarization which manifests it self as electron population imbalance of different sublattices can be detected by optical spectroscopy measurements.

Pseudo-Edelstein effect in disordered silicene.

The 'pseudo-Edelstein' effect by which charge currentJxconverts to pseudo-spin polarization,τz, 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.

Ellipsometric spectroscopy of rubidium vapor cell at near-normal incidence.

Various efforts have been made to overcome Doppler broadening in hyperfine measurement limitations in the atomic vapors spectroscopy and associated applications. The present study measured and calculated hyperfine resolved ellipsometric parameters through the near-normal reflectance spectra of the rubidium vapor cell in two experimental setups based on continuous and modulated pathway. The results indicated that valuable information could be extracted from the ellipsometric parameters about the atomic medium. Change in the ellipsometric parameters in each transition line confirms the existence of the elliptical polarization of the reflected light when it is exposed to the alkali metal vapor. Our results show that the ellipticity at 5S1/2 (Fg = 1, 2) → 5P1/2 (Fe = 1, 2) hyperfine transitions of 87Rb (D1 line) is small, and accordingly hyperfine transitions between the ground 5S1/2 (Fg = 2, 3) and excited 5P1/2 (Fe = 2, 3) states of the 85Rb isotope are considerable. These ellipsometric parameters, as phase difference, can trace the behavior of the relative orientation of the electric field and atom velocity in the interface based on van der Waals dipole-dipole interaction and is directly proportional to the strength of the light-matter interaction which extremely useful instead complicated atomic spectroscopic methods.