8,729 research outputs found
CMS experiment at the LHC: Commissioning and early physics
The CMS collaboration used the past year to greatly improve the level of
detector readiness for the first collisions data. The acquired operational
experience over this year, large gains in understanding the detector and
improved preparedness for early physics will be instrumental in minimizing the
time from the first collisions to first LHC physics. The following describes
the status of the CMS experiment and outlines early physics plans with the
first LHC data.Comment: To appear in the Proceedings of the 21st Rencontres de Blois: Windows
on the Universe, Blois, France, 21-27 Jun 200
Tensor form of magnetization damping
A tensor form of phenomenological damping is derived for small magnetization
motions. This form reflects basic physical relaxation processes for a general
uniformly magnetized particle or film. Scalar Landau-Lifshitz damping is found
to occur only for two special cases of system symmetry.Comment: Paper HA-03 presented at MMM'01, to be published in J. Appl. Phy
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
Microscopic mechanisms of magnetization reversal
Two principal scenarios of magnetization reversal are considered. In the
first scenario all spins perform coherent motion and an excess of magnetic
energy directly goes to a nonmagnetic thermal bath. A general dynamic equation
is derived which includes a tensor damping term similar to the
Bloch-Bloembergen form but the magnetization magnitude remains constant for any
deviation from equilibrium. In the second reversal scenario, the absolute value
of the averaged sample magnetization is decreased by a rapid excitation of
nonlinear spin-wave resonances by uniform magnetization precession. We have
developed an analytic k-space micromagnetic approach that describes this entire
reversal process in an ultra-thin soft ferromagnetic film for up to 90^{o}
deviation from equilibrium. Conditions for the occurrence of the two scenarios
are discussed
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