1,869 research outputs found
Non-uniform thermal magnetization noise in thin films: application to GMR heads
A general scheme is developed to analyze the effect of non-uniform thermal
magnetization fluctuations in a thin film. The normal mode formalism is
utilized to calculate random magnetization fluctuations. The magnetization
noise is proportional to the temperature and inversely proportional to the film
volume. The total noise power is the sum of normal mode spectral noises and
mainly determined by spin-wave standing modes with an odd number of
oscillations. The effect rapidly decreases with increasing mode number. An
exact analytical calcutaion is presented for a two-cell model.Comment: Paper for MMM'01, CB-10, to be published in J. Appl. Phy
Turbulent skin friction and heat-transfer charts adapted from the Spalding and Chi method
Local and average skin friction and heat transfer on flat plates in air - chart
Thermal stability of coupled ferromagnetic and superparamagnetic particles
We consider a single-domain ferromagnetic particle with uniaxial anisotropy
coupled to a single-domain soft ferromagnetic particle (superparamagnetic
particle). The problem of thermally agitated magnetization reversal in this
case can be reduced to the random magnetization dynamics of the first particle
with an effectively larger anisotropy field. The magnetic external field is
also altered in a manner that depends on the sign of the coupling and can be
either enhanced or suppressed.Comment: 3 pages, 2 figures, presented at MMM'0
Impurity relaxation mechanism for dynamic magnetization reversal in a single domain grain
The interaction of coherent magnetization rotation with a system of two-level
impurities is studied. Two different, but not contradictory mechanisms, the
`slow-relaxing ion' and the `fast-relaxing ion' are utilized to derive a system
of integro-differential equations for the magnetization. In the case that the
impurity relaxation rate is much greater than the magnetization precession
frequency, these equations can be written in the form of the Landau-Lifshitz
equation with damping. Thus the damping parameter can be directly calculated
from these microscopic impurity relaxation processes
Fluctuation-dissipation considerations and damping models for ferromagnetic materials
The role of fluctuation-dissipation relations (theorems) for the
magnetization dynamics with Landau-Lifshitz-Gilbert and Bloch-Bloembergen
damping terms are discussed. We demonstrate that the use of the Callen-Welton
fluctuation-dissipation theorem that was proven for Hamiltonian systems can
give an inconsistent result for magnetic systems with dissipation
Probing BFKL Dynamics in the Dijet Cross Section at Large Rapidity Intervals in ppbar Collisions at sqrt{s}=1800 and 630 GeV
Inclusive dijet production at large pseudorapidity intervals (delta_eta)
between the two jets has been suggested as a regime for observing BFKL
dynamics. We have measured the dijet cross section for large delta_eta in ppbar
collisions at sqrt{s}=1800 and 630 GeV using the DO detector. The partonic
cross section increases strongly with the size of delta_eta. The observed
growth is even stronger than expected on the basis of BFKL resummation in the
leading logarithmic approximation. The growth of the partonic cross section can
be accommodated with an effective BFKL intercept of
a_{BFKL}(20GeV)=1.65+/-0.07.Comment: Published in Physical Review Letter
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