35,306 research outputs found
Magnetization of La(2-x)Sr(x)NiO(4+ delta) (0 < x < 0.5) and observation of novel memory effects
We have studied the magnetization of a series of spin-charge ordered
La(2-x)Sr(x)NiO(4+delta) single crystals with 0 < x < 0.5. For fields applied
parallel to the ab plane there is a large irreversibility below a temperature
T(F1) ~ 50 K and a smaller irreversibility that persists up to near the charge
ordering temperature. We observed a novel memory effect in the thermo-remnant
magnetization across the entire doping range. We found that these materials
retain a memory of the temperature at which an external field was removed, and
that there is a pronounced increase in the thermo-remnant magnetization when
the system is warmed through a spin reorientation transition.Comment: 11 pages, 12 figure
First-principles characterization of ferromagnetic Mn5Ge3 for spintronic applications
In the active search for potentially promising candidates for spintronic
applications, we focus on the intermetallic ferromagnetic Mn5Ge3 compound and
perform accurate first-principles FLAPW calculations within density functional
theory. Through a careful investigation of the bulk electronic and magnetic
structure, our results for the total magnetization, atomic magnetic moments,
metallic conducting character and hyperfine fields are found to be in good
agreement with experiments, and are elucidated in terms of a hybridization
mechanism and exchange interaction. In order to assess the potential of this
compound for spin-injection purposes, we calculate Fermi velocities and degree
of spin-polarization; our results predict a rather high spin-injection
efficiency in the diffusive regime along the hexagonal c-axis. Magneto-optical
properties, such as L_2,3 X-ray magnetic circular dichroism, are also reported
and await comparison with experimental data.Comment: 10 pages with 6 figures, to appear in Phys. Rev.
Cost-efficient manufacturing of composite structures
The Advanced Composites Technology (ACT) program is seeking research breakthroughs that will allow structures made of graphite epoxy materials to replace metals in the wings and fuselages of future aircrafts. NASA's goals are to reduce acquisition cost by 20 to 25 percent, structural weight for a resized aircraft by 40 to 50 percent, and the number of parts by half compared to current production aluminum aircraft. The innovative structural concepts, materials, and fabrication techniques emerging from the ACT program are described, and the relationship between aerospace developments and industrial, commercial, and sporting goods applications are discussed
Replenish the source within: Rescuing tumor-infiltrating lymphocytes by double checkpoint blockade.
We have recently reported that the PD-1 and CTLA4 signaling pathways are active in both effector and regulatory T cells, causing profound immune dysfunctions in the tumor microenvironment. In line with this notion, the dual blockade of PD-1- and CTLA4-conveyed signals may exert robust therapeutic effects. Here, we discuss the mechanisms possibly underlying such a synergic interaction
Thin Films of 3He -- Implications on the Identification of 3 He -A
Recently the identification of 3He-A with the axial state has been
questioned. It is suggested that the A-phase can actually be in the axiplanar
state. We point out in the present paper that experiments in a film geometry
may be useful to distinguish the above two possibilities. In particular a
second order phase transition between an axial and an axiplanar state would
occur as a function of thickness or temperature.Comment: 3 pages, no figures latex- revtex aps accepted by J. of Low
Temperature Physic
Research Reports: 1983 NASA/ASEE Summer Faculty Fellowship Program
Thirty-five technical reports contain results of investigations in information and electronic systems; materials and processing; systems dynamics; structures and propulsion; and space sciences. Ecology at KSC, satellite de-spin, and the X-ray source monitor were also studied
More pieces of the puzzle: Chemistry and substructures in the Galactic thick disk
We present a study of the chemical abundances of Solar neighbourhood stars
associated to dynamical structures in the Milky Way's (thick) disk. These stars
were identified as overdensity in the eccentricity range 0.3< ecc < 0.5 in the
Copenhagen-Geneva Survey by Helmi et al. (2006). We find that the stars with
these dynamical characteristics do not constitute a homogeneous population. A
relatively sharp transition in dynamical and chemical properties appears to
occur at a metallicity of [Fe/H] ~ -0.4. Stars with [Fe/H] > -0.4 have mostly
lower eccentricities, smaller vertical velocity dispersions, are alpha-enhanced
and define a rather narrow sequence in [alpha/Fe] vs [Fe/H], clearly distinct
from that of the thin disk. Stars with [Fe/H] < -0.4 have a range of
eccentricities, are hotter vertically, and depict a larger spread in
[alpha/Fe]. We have also found tentative evidence of substructure possibly
associated to the disruption of a metal-rich star cluster. The differences
between these populations of stars is also present in e.g. [Zn/Fe], [Ni/Fe] and
[SmII/Fe], suggesting a real physical distinction.Comment: Astrophysical Journal in press. 5 pages, 4 figure
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