21 research outputs found
Large-scale magnetic fields from inflation due to a -even Chern-Simons-like term with Kalb-Ramond and scalar fields
We investigate the generation of large-scale magnetic fields due to the
breaking of the conformal invariance in the electromagnetic field through the
-even dimension-six Chern-Simons-like effective interaction with a fermion
current by taking account of the dynamical Kalb-Ramond and scalar fields in
inflationary cosmology. It is explicitly demonstrated that the magnetic fields
on 1Mpc scale with the field strength of G at the present time
can be induced.Comment: 18 pages, 6 figures, version accepted for publication in Eur. Phys.
J.
Generation of the large scale magnetic fields by coupling to curvature and dilaton field
We investigate the generation of large scale magnetic fields in the universe from quantum fluctuations that are produced in the inflationary stage. By coupling these quantum fluctuations to the dilaton field and Ricci scalar, we show that the magnetic fields with the strength observed today can be produced. We consider two situations. First, the evolution of dilaton ends by starting the reheating stage. Second, the dilaton continues its evolution after reheating and then decays. We here consider the first case. In both cases, we come back to the usual Maxwell equations after inflation and then calculate present magnetic fields
Three-fold Symmetric Doping Mechanism in GaAs Nanowires
A new dopant incorporation mechanism in Ga-assisted GaAs nanowires
grown by molecular beam epitaxy is reported. Off-axis electron holography
revealed that p-type Be dopants introduced in situ during molecular
beam epitaxy growth of the nanowires were distributed inhomogeneously
in the nanowire cross-section, perpendicular to the growth direction.
The active dopants showed a remarkable azimuthal distribution along
the (111)B flat top of the nanowires, which is attributed to preferred
incorporation along 3-fold symmetric truncated facets under the Ga
droplet. A diffusion model is presented to explain the unique radial
and azimuthal variation of the active dopants in the GaAs nanowires
Measuring the Magnetic Induction of Isolated CoFeB Nanowires by Off-Axis Electron Holography
Extended abstract of a paper presented at Microscopy and Microanalysis 2012 in Phoenix, Arizona, USA, July 29 – August 2, 2012.</jats:p