407 research outputs found
Study of the Large-scale Temperature Structure of the Perseus Cluster with Suzaku
We report on a study of the large-scale temperature structure of the Perseus
cluster with Suzaku, using the observational data of four pointings of 30'
offset regions, together with the data from the central region. Thanks to the
Hard X-ray Detector (HXD-PIN: 10 - 60 keV), Suzaku can determine the
temperature of hot galaxy clusters. We performed the spectral analysis, by
considering the temperature structure and the collimator response of the PIN
correctly. As a result, we found that the upper limit of the temperature in the
outer region is 14 keV, and an extremely hot gas, which was reported for
RXJ 1347.5-1145 and A 3667, was not found in the Perseus cluster. This
indicates that the Perseus cluster has not recently experienced a major merger.Comment: 17 pages, 25 figures, accepted for Publications of the Astronomical
Society of Japan, references adde
Local density of states as a probe for tunneling magnetoresistance effect: application to ferrimagnetic tunnel junctions
We investigate the tunneling magnetoresistance (TMR) effect using the lattice
models which describe the magnetic tunnel junctions (MTJ). First, taking a
conventional ferromagnetic MTJ as an example, we show that the product of the
local density of states (LDOS) at the center of the barrier traces the TMR
effect qualitatively. The LDOS inside the barrier has the information on the
electrodes and the electron tunneling through the barrier, which enables us to
easily evaluate the tunneling conductance more precisely than the conventional
Julliere's picture. We then apply this method to the MTJs with collinear
ferrimagnets and antiferromagnets. We find that the TMR effect in the
ferrimagnetic and antiferromagnetic MTJs changes depending on the interfacial
magnetic structures originating from the sublattice structure, which can also
be captured by the LDOS. Our findings will reduce the computational cost for
the qualitative evaluation of the TMR effect, and be useful for a broader
search for the materials which work as the TMR devices showing high
performance.Comment: 11 pages, 11 figure
A novel scanning Thermal Microscopy System
MEMS 2007, Kobe, Japan, 21-25 January 200
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