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Controlled transportation of mesoscopic particles by enhanced spin orbit interaction of light in an optical trap
We study the effects of the spin orbit interaction (SOI) of light in an
optical trap and show that the propagation of the tightly focused trapping beam
in a stratified medium can lead to significantly enhanced SOI. For a plane
polarized incident beam the SOI manifests itself by giving rise to a strong
anisotropic linear diattenuation effect which produces polarization-dependent
off-axis high intensity side lobes near the focal plane of the trap. Single
micron-sized asymmetric particles can be trapped in the side lobes, and
transported over circular paths by a rotation of the plane of input
polarization. We demonstrate such controlled motion on single pea-pod shaped
single soft oxometalate (SOM) particles of dimension around m
over lengths up to 15 m . The observed effects are supported by
calculations of the intensity profiles based on a variation of the Debye-Wolf
approach. The enhanced SOI could thus be used as a generic means of
transporting mesoscopic asymmetric particles in an optical trap without the use
of complex optical beams or changing the alignment of the beam into the trap.Comment: 9 pages, 7 figure
Hall Mobility of Tellurium Films Deposited on BaTiO3 Crystal
The measurements of electrical resistivity and Hall coefficient of tellurium films deposited on polarised barium titanate single crystals have been reported; the results on glass and mica substrate are also included for comparison. The results yield a value of surface state density for tellurium to be 15 X 1O 14/cm2 volt and the energy of the surface states 0.09 e.v. below the mid gap position
Local and global persistence exponents of two quenched continuous lattice spin models
Local and global persistence exponents associated with zero temperature
quenched dynamics of two dimensional XY model and three dimensional Heisenberg
model have been estimated using numerical simulations. We have used the method
of block persistence to find both global and local exponents simultaneously (in
a single simulation). Temperature universality of both the exponents for three
dimensional Heisenberg model has been confirmed by simulating the stochastic
(with noise) version of the equation of motion. The noise amplitudes added were
small enough to retain the dynamics below criticality. In the second part of
our work we have studied scaling associated with correlated persistence sites
in the three dimensional Heisenberg model in the later stages of the dynamics.
The relevant length scale associated with correlated persistent sites was found
to behave in a manner similar to the dynamic length scale associated with the
phase ordering dynamics.Comment: 20 pages, 7 figure
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