102 research outputs found
The electronic structures and magnetic properties of perovskite ruthenates from constrained orbital hybridization calculations
We introduce a method to analyze the effect of hybridization by shifting
corresponding atomic levels using external potentials. Based on this approach,
we study perovskite ruthenates,\ and unambiguously identify that the covalency
between the \textit{A}-site cation and O ion will modify the Ru-O hybridization
and change the density of state at Fermi level, consequently affect the
magnetic properties significantly. We also study the effect of pressure and
reveal that hydrostatic pressure has a small effect on the Ru-O-Ru bond angle
of SrRuO, while it will decrease the Ru-O length and increase the band
width significantly. Therefore, the magnetic ordering temperature will decrease
monotonically with pressure
Novel critical exponent of magnetization curves near the ferromagnetic quantum phase transitions of Sr1-xAxRuO3 (A = Ca, La0.5Na0.5, and La)
We report a novel critical exponent delta=3/2 of magnetization curves
M=H^{1/delta} near the ferromagnetic quantum phase transitions of Sr1-xAxRuO3
(A = Ca, La0.5Na0.5, and La), which the mean field theory of the
Ginzburg-Landau-Wilson type fails to reproduce. The effect of dirty
ferromagnetic spin fluctuations might be a key.Comment: 4 pages, 5 figure
Photoproduction of Lambda(1405) and Sigma^{0}(1385) on the proton at E_\gamma = 1.5-2.4 GeV
Differential cross sections for and reactions have been measured in the photon energy range
from 1.5 to 2.4 GeV and the angular range of for the
scattering angle in the center-of-mass system. This data is the first
measurement of the photoproduction cross section. The
lineshapes of \LamS measured in and decay modes
were different with each other, indicating a strong interference of the isospin
0 and 1 terms of the scattering amplitudes. The ratios of \LamS
production to \SigS production were measured in two photon energy ranges: near
the production threshold ( GeV) and far from it ( GeV). The observed ratio decreased in the higher photon energy
region, which may suggest different production mechanisms and internal
structures for these hyperon resonances
- …