14,120 research outputs found
Effect of sintering temperature under high pressure in the uperconductivity for MgB2
We report the effect of the sintering temperature on the superconductivity of
MgB2 pellets prepared under a high pressure of 3 GPa. The superconducting
properties of the non-heated MgB2 in this high pressure were poor. However, as
the sintering temperature increased, the superconducting properties were vastly
enhanced, which was shown by the narrow transition width for the resistivity
and the low-field magnetizations. This shows that heat treatment under high
pressure is essential to improve superconducting properties. These changes were
found to be closely related to changes in the surface morphology observed using
scanning electron microscopy.Comment: 3 Pages including 3 figure
Bogomol'nyi equations for solitons in Maxwell-Chern-Simons gauge theories with the magnetic moment interaction term
Without assuming rotational invariance, we derive Bogomol'nyi equations for
the solitons in the abelian Chern-Simons gauge theories with the anomalous
magnetic moment interaction. We also evaluate the number of zero modes around a
static soliton configuration.Comment: 9 pages, Revtex, SNUTP-94/6
Spin Hall torque magnetometry of Dzyaloshinskii domain walls
Current-induced domain wall motion in the presence of the
Dzyaloshinskii-Moriya interaction (DMI) is experimentally and theoretically
investigated in heavy-metal/ferromagnet bilayers. The angular dependence of the
current-induced torque and the magnetization structure of Dzyaloshinskii domain
walls are described and quantified simultaneously in the presence of in-plane
fields. We show that the DMI strength depends strongly on the heavy metal,
varying by a factor of 20 between Ta and Pa, and that strong DMI leads to wall
distortions not seen in conventional materials. These findings provide
essential insights for understanding and exploiting chiral magnetism for
emerging spintronics applications
Scaling laws for the photo-ionisation cross section of two-electron atoms
The cross sections for single-electron photo-ionisation in two-electron atoms
show fluctuations which decrease in amplitude when approaching the
double-ionisation threshold. Based on semiclassical closed orbit theory, we
show that the algebraic decay of the fluctuations can be characterised in terms
of a threshold law as with exponent
obtained as a combination of stability exponents of the triple-collision
singularity. It differs from Wannier's exponent dominating double ionisation
processes. The details of the fluctuations are linked to a set of infinitely
unstable classical orbits starting and ending in the non-regularisable triple
collision. The findings are compared with quantum calculations for a model
system, namely collinear helium.Comment: 4 pages, 1 figur
A Spectral Line Survey from 138.3 to 150.7 GHZ toward Orion-KL
We present the results of a spectral line survey from 138.3 to 150.7 GHz
toward Orion-KL. The observations were made using the 14 m radio telescope of
Taeduk Radio Astronomy Observatory. Typical system temperatures were between
500 and 700 K, with the sensitivity between K in units of .
A total of 149 line spectra are detected in this survey. Fifty lines have
been previously reported, however we find 99 new detections. Among these new
lines, 32 are `unidentified', while 67 are from molecular transitions with
known identifications. There is no detection of H or He recombination lines.
The identified spectra are from a total of 16 molecular species and their
isotopic variants. In the range from 138.3 to 150.7 GHz, the strongest spectral
line is the J=3-2 transition of CS molecule, followed by transitions of the
, , , and . Spectral lines from
the large organic molecules such as , , , and are prominent; with 80 % of the
identified lines arising from transitions of these molecules. The rotational
temperatures and column densities are derived using the standard rotation
diagram analysis for (), , and with and . These estimates are fairly comparable to the values for the
same molecule in other frequency regions by other studies.Comment: 10 figures, 2 tex files for a manuscript and tables, accepted to Ap
- …