5,372 research outputs found
Generation of Magnetic Field in the Pre-recombination Era
We study the possibility of generating magnetic fields during the evolution
of electron, proton, and photon plasma in the pre-recombination era. We show
that a small magnetic field can be generated in the second order of
perturbation theory for scalar modes with adiabatic initial conditions. The
amplitude of the field is \la 10^{-30} \rm G at the present epoch for scales
from sub-kpc to \ga 100 \rm Mpc.Comment: 8 page
Influence of field-like torque in synchronization of spin torque oscillators
The magnetization dynamics of two parallelly coupled spin torque oscillators,
destabilization of steady states and removal of multistability, are
investigated by taking into account the influence of field-like torque. It is
shown that the existence of such torque can cancel the effect of damping and
can, therefore, cause the oscillators to exhibit synchronized oscillations in
response to direct current. Further, our results show that the presence of
field-like torque enhances the power and Q-factor of the synchronized
oscillations. The validity of the above results is confirmed by numerical and
analytical studies based on the stochastic Landau-Lifshitz-Gilbert-Slonczewski
equation.Comment: 10 pages, 10 figures, Accepted for Publication in IEEE Transactions
on Magnetic
Theoretical spectroscopic studies of the atomic transitions and lifetimes of low-lying states in Ti IV
The astrophysically important electric quadrupole (E2) and magnetic dipole
(M1) transitions for the low-lying states of triply ionized titanium (Ti IV)
are calculated very accurately using a state-of-art all-order many-body theory
called Coupled Cluster (CC) theory in the relativistic frame-work. Different
many-body correlations of the CC theory has been estimated by studying the core
and valence electron excitations to the unoccupied states. The calculated
excitation energies of different states are in very good agreement with the
measurements. Also we compare our calculated electric dipole (E1) transition
amplitudes of few transitions with recent many-body calculations by different
groups. We have also carried out the calculations for the lifetimes of the
low-lying states of Ti IV. A long lifetime is found for the first excited
3d state, which suggested that Ti IV may be one of the useful
candidates for many important studies. Most of the results reported here are
not available in the literature, to the best of our knowledge.Comment: 15 pages submitted to J. Phys.
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