36,323 research outputs found
Time dependent nonclassical properties of even and odd nonlinear coherent states
We construct even and odd nonlinear coherent states of a parametric
oscillator and examine their nonclassical properties.It has been shown that
these superpositions exhibit squeezing and photon antibunching which change
with time.Comment: 3 eps figure
Vortex Matter and its Phase Transitions
The mixed state of type II superconductors has magnetic flux penetrating the
sample in the form of vortices, with each vortex carrying an identical quantum
of flux. These vortices generally form a triangular lattice under weak mutually
repulsive forces; the lattice spacing can be easily varied over many orders of
magnitude by varying the external magnetic field. The elastic moduli of this
lattice are small and this soft vortex matter can undergo phase transitions
like normal matter, but with thermal fluctuations and underlying defects
playing an important role. We discuss experimental studies on vortex matter
phase transitions, with some emphasis on DC magnetisation measurements
investigating the nature of the phase transition.Comment: 11 pages and 4 figure
Peak effect in CeRu:history dependence and supercooling
We present experimental results on single crystal CeRu showing that the
extent of history dependence of peak-effect depends on the path followed in the
space of field (H) and temperature (T). The (H,T) regime over which history
effect is observed is larger if the vortex lattice is prepared by lowering T
from above T in constant H i.e. by field cooling. We compare this history
effect with the very recently reported history dependence of peak-effect in
detwinned single crystals of YBaCuO, highlighting the similarities and
differences. We discuss the possibility of a first order vortex solid-solid
transition in CeRu within the realm of recent theoretical developments in
the field of vortex matter.Comment: 21 pages, 5 figures; submitted to Phys. Rev. B on 9th Feb. 200
Kinetic arrest of the first order ferromagnetic to antiferromagnetic transition in Ce(FeRu) : formation of a magnetic-glass
We present results of dc magnetization and magnetic relaxation study showing
the kinetic arrest of a first order ferromagnetic to antiferromagnetic
transition in Ce(FeRu). This leads to the formation of a
non-ergodic glass-like magnetic state. The onset of the magnetic-glass
transformation is tracked through the slowing down of the magnetization
dynamics. This glassy state is formed with the assistance of an external
magnetic field and this is distinctly different from the well known
'spin-glass' state.Comment: 10 pages of text and 4 figure
Calculation of minor hysteresis loops under metastable to stable transformations in vortex matter
We present a model in which metastable supercooled phase and stable
equilibrium phase of vortex matter coexist in different regions of a sample.
Minor hysteresis loops are calculated with the simple assumption of the two
phases of vortex matter having field-independent critical current densities. We
use our earlier published ideas that the free energy barrier separating the
metastable and stable phases reduces as the magnetic induction moves farther
from the first order phase transition line, and that metastable to stable
transformations occur in local regions of the sample when the local energy
dissipation exceeds a critical value. Previously reported anomalous features in
minor hysteresis loops are reproduced, and calculated field profiles are
presented.Comment: 9pages, 7 figure
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