1,058 research outputs found
Raman scattering studies of spin, charge, and lattice dynamics in Ca_{2-x}Sr_{x}RuO_{4} (0 =< x < 0.2)
We use Raman scattering to study spin, charge, and lattice dynamics in
various phases of Ca_{2-x}Sr_{x}RuO_{4}. With increasing substitution of Ca by
Sr in the range 0 =< x < 0.2, we observe (1) evidence for an increase of the
electron-phonon interaction strength, (2) an increased temperature-dependence
of the two-magnon energy and linewidth in the antiferromagnetic insulating
phase, and (3) evidence for charge gap development, and hysteresis associated
with the structural phase change, both of which are indicative of a first-order
metal-insulator transition (T_{MI}) and a coexistence of metallic and
insulating components for T < T_{MI}
Orbital Dependent Phase Control in Ca2-xSrxRuO4
We present first-principles studies on the orbital states of the layered
perovskites CaSrRuO. The crossover from antiferromagnetic (AF)
Mott insulator for to nearly ferromagnetic (FM) metal at is
characterized by the systematic change of the orbital occupation. For the
AF side (), we present firm evidence for the ferro-orbital
ordering. It is found that the degeneracy of (or ) states is
lifted robustly due to the two-dimensional (2D) crystal-structure, even without
the Jahn-Teller distortion of RuO. This effect dominates, and the
cooperative occupation of orbital is concluded. In contrast to recent
proposals, the resulting electronic structure explains well both the observed
X-ray absorption spectra and the double peak structure of optical conductivity.
For the FM side (), however, the orbital with half filling opens a
pseudo-gap in the FM state and contributes to the spin =1/2 moment (rather
than =1 for =0.0 case) dominantly, while states are itinerant
with very small spin polarization, explaining the recent neutron data
consistently.Comment: 17 pages, 5 figure
Vaccinia virus binds to the scavenger receptor MARCO on the surface of keratinocytes.
Patients with altered skin immunity, such as individuals with atopic dermatitis (AD), can have a life-threatening disruption of the epidermis known as eczema vaccinatum after vaccinia virus (VV) infection of the skin. Here, we sought to better understand the mechanism(s) by which VV associates with keratinocytes. The class A scavenger receptor known as MARCO (macrophage receptor with collagenous structure) is expressed on human and mouse keratinocytes and found to be abundantly expressed in the skin of patients with AD. VV bound directly to MARCO, and overexpression of MARCO increased susceptibility to VV infection. Furthermore, ligands with affinity for MARCO, or excess soluble MARCO, competitively inhibited VV infection. These findings indicate that MARCO promotes VV infection and highlights potential new therapeutic strategies for prevention of VV infection in the skin
Orbital-selective Mass Enhancements in Multi-band CaSrRuO Systems Analyzed by the Extended Drude Model
We investigated optical spectra of quasi-two-dimensional multi-band CaSrRuO systems. The extended Drude model analysis on the
ab-plane optical conductivity spectra indicates that the effective mass should
be enhanced near . Based on the sum rule argument, we showed that the
orbital-selective Mott-gap opening for the bands, the widely
investigated picture, could not be the origin of the mass enhancement. We
exploited the multi-band effects in the extended Drude model analysis, and
demonstrated that the intriguing heavy mass state near should come from
the renormalization of the band.Comment: 4 figure
Dropped in Capacity and Traffic Speed of Urban Arterial: a Case Study at U-Turn Section in Aceh Province, Indonesia
- Dropped in traffic capacity and travel speed during congestion were studied at a u-turn section on an arterial road in Indonesia. Traffic characteristics during congestion were analyzed using oblique cumulative plots and breakdown method. Both approaches are time series treatment between cumulative vehicles arrival versus time contracted from data recorded by video tape. Studies were conducted in both morning and evening peak hours on three regular weekdays. This study found traffic breakdown condition during the peak periods; the breakdown lasted on average 40 minutes. It was found that capacity during traffic breakdown drops in the range 8-9 percent from the before-breakdown capacity. Similarly, during the breakdown, speed drops on average 10 percent from the before condition. Several alternatives were selected and tested for improving existing conditions. It was found that adding a 50m pocket lane would help improving the existing situation by reducing the delay to 69 percent, increasing speed to 39 percent, and improving capacity to 11 percent compared to the result of simulation an existing conditio
Filling Control of the Mott Insulator Ca2RuO4
We have grown single crystals of electron doping system Ca2-xLaxRuO4 (0.00 <=
x <= 0.20) by a floating zone method. The first order metal/non-metal
transition and canted antiferromagnetic ordering occur for 0.00 < x < 0.15,
similar to those in the bandwidth controlled system Ca2-xSrxRuO4 (CSRO).
However, comparing with CSRO, we found a rather different metallic ground state
adjacent to the non-metallic ground state with canted antiferromagnetic order.
Instead of short-range antiferromagnetic correlation found in CSRO (0.20 <= x <
0.50), the metallic ground state of the present system is characterized by
strong ferromagnetic correlation.Comment: 8 pages, 8 figures (eps), submitted to J. Phys. Soc. Jp
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