Magnetoelectric Properties of Pb Free Bi2FeTiO6: A Theoretical Investigation

The structural, electronic, magnetic and ferroelectric properties of Pb free double perovskite multiferroic Bi2FeTiO6 are investigated using density functional theory within the general gradient approximation (GGA) method. Our structural optimization using total energy calculations for different potential structures show a minimum energy for a non-centrosymmetric rhombohedral structure with R3 space group. Bi2FeTiO6 is found to be an antiferromagnetic insulator with C-type magnetic ordering with bandgap value of 0.3 eV. The calculated magnetic moment of 3.52 \mu_B at Fe site shows the high spin arrangement of 3d electrons which is also confirmed by our orbital projected density of states analysis. We have analyzed the characteristics of bonding present between the constituents of Bi2FeTiO6 with the help of calculated partial density of states and Born effective charges. The ground state of the nearest centrosymmetric structure is found to be a G-type antiferromagnet with half metallicity showing that by the application of external electric field we can not only get a polarized state but also change the magnetic ordering and electronic structure in the present compound indicating strong magnetoelectric coupling. The cation sites the coexistence of Bi 6s lone pair (bring disproportionate charge distribution) and Ti4+ d0 ions which brings covalency produces off-center displacement and favors a non-centrosymmetric ground state and thus ferroelectricity. Our Berry phase calculation gives a polarization of 48 \muCcm-2 for Bi2FeTiO6.Comment: 4 pages, 5 picture

Beam polarization effects in the radiative production of lightest neutralinos in e+e−e^+ e^- collisions in supersymmetric grand unified models

We study the production of the lightest neutralinos in the process $e^+ e^- \rightarrow \chi_1^0 \chi_1^0 \gamma$ in supersymmetric grand unified models for the International Linear Collider Energies with longitudinally polarized beams. We consider cases where the standard model gauge group is unified into the grand unified gauge groups SU(5), or SO(10). We have carried out a comprehensive study of this process in the SU(5) and SO(10) grand unified theories which includes the QED radiative corrections. We compare and contrast the dependence of the signal cross section on the grand unified gauge group, and on the different representations of the grand unified gauge group, when the the electron and positron beams are longitudinally polarized. To assess the feasibility of experimentally observing the radiative production process, we have also considered in detail the background to this process coming from the radiative neutrino production process $e^+ e^- \rightarrow \nu \bar\nu \gamma$ with longitudinally polarized electron and positron beams. In addition we have also considered the supersymmetric background coming from the radiative production of scalar neutrinos in the process $e^+ e^- \rightarrow \tilde \nu \tilde\nu^* \gamma$ with longitudinally polarized beams. The process can be a major background to the radiative production of neutralinos when the scalar neutrinos decay invisibly.Comment: 26 pages, 18 figures; typos and misprints corrected; results and conclusions unchanged; this paper is a sequel to and draws material from the paper arXiv:1210.647

Visual Analysis Of Children Books Illustration As a Psychiatric Therapy

One of the most acute urban problems is the emergence of psychiatric problems caused by the acceleration of daily routine. These psychiatric problems not only suffered by adults, but also children. These children generally have a problem called B.L.A.S.T. (Bored, Lonely, Angry-Afraid, Sad, Tired). To overcome this problem, there are a number of ways, including reading. Since 1802, Benjamin Rush, the father of United States psychiatry, recommends reading as part of therapy for patients with mental disorders. This therapy also applies for children by adding more illustrations wihin the books. This study analyzed three illustrated books that read by children in Indonesia from ages 7-13 years. The Illustrations analyzed by Roland Barthes's semiotic approach, to get conclusions regarding how illustration have a positive psychiatric therapy impact on children. The finding and results based on semiotic approach that, books mentioned above have the potential to overcome of B.L.A.S.T. because it contains two functions, education and entertainment. This assumption supported by theoritical view of psychologist Jean Piaget, things that educate and entertain are two important elements as a therapy for many kinds of psychiatric problems. Keywords: Children, Illustration, Psychology,Semiotics, B.L.A.S.