14,320 research outputs found
Unusual Coupling Between Field-induced Spin Fluctuations and Spin Density Wave in Intermetallic CeAg2Ge2
We report on the experimental evidences for an unusual coupling between the
magnetic field- induced fluctuations of correlated Ce-ions coinciding with the
discontinuous movement of the underlying spin density wave in the intermetallic
rare earth compound CeAg2Ge2. The measurements performed using neutron
scattering and magnetic Gruneisen ratio methods suggest that the coupling
onsets at H= 2.7 T, T < 3.8 K and persists to the lowest measurement
temperature T ~ 0.05 K. These measurements suggest a new mechanism behind the
spin fluctuations which can affect the intrinsic properties of the system.Comment: 4 pages, 4 figures, Strongly correlated electrons syste
Determination of the Spin-Hall-Effect-Induced and the Wedged-Structure-Induced Spin Torque Efficiencies in Heterostructures with Perpendicular Magnetic Anisotropy
We report that by measuring current-induced hysteresis loop shift versus
in-plane bias magnetic field, the spin Hall effect (SHE) contribution of the
current-induced effective field per current density, , can be
estimated for Pt and Ta-based magnetic heterostructures with perpendicular
magnetic anisotropy (PMA). We apply this technique to a Pt-based sample with
its ferromagnetic (FM) layer being wedged-deposited and discover an extra
effective field contribution, , due to the asymmetric nature of
the deposited FM layer. We confirm the correlation between and
the asymmetric depinning process in FM layer during magnetization switching by
magneto-optical Kerr (MOKE) microscopy. These results indicate the possibility
of engineering deterministic spin-orbit torque (SOT) switching by controlling
the symmetry of domain expansion through the materials growth process
Grain-boundary grooving and agglomeration of alloy thin films with a slow-diffusing species
We present a general phase-field model for grain-boundary grooving and
agglomeration of polycrystalline alloy thin films. In particular, we study the
effects of slow-diffusing species on grooving rate. As the groove grows, the
slow species becomes concentrated near the groove tip so that further grooving
is limited by the rate at which it diffuses away from the tip. At early times
the dominant diffusion path is along the boundary, while at late times it is
parallel to the substrate. This change in path strongly affects the
time-dependence of grain boundary grooving and increases the time to
agglomeration. The present model provides a tool for agglomeration-resistant
thin film alloy design. keywords: phase-field, thermal grooving, diffusion,
kinetics, metal silicidesComment: 4 pages, 6 figure
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Capacity market design options: a dynamic capacity investment model and a GB case study
Rising feed-in from renewable energy sources decreases margins, load factors, and thereby profitability of conventional generation in several electricity markets around the world. At the same time, conventional generation is still needed to ensure security of electricity supply. Therefore, capacity markets are currently being widely discussed as a measure to ensure generation adequacy in markets such as France, Germany, and the United States (e.g., Texas), or even implemented for example in Great Britain. We assess the effect of different capacity market design options in three scenarios: 1) no capacity market, 2) a capacity market for new capacity only, and 3) a capacity market for new and existing capacity. We compare the results along the three key dimensions of electricity policy ��� affordability, reliability, and sustainability. In a Great Britain case study we find that a capacity market increases generation adequacy since it provides incentives for new generation investments. Furthermore, our results show that a capacity market can lower the total bill of generation because it can reduce lost load and the potential to exercise market power. Additionally, we find that a capacity market for new capacity only is cheaper than a capacity market for new and existing capacity because it remunerates fewer generators in the first years after its introduction.renewable energy source
Scanning tunneling spectroscopy of superconducting LiFeAs single crystals: Evidence for two nodeless energy gaps and coupling to a bosonic mode
The superconducting compound, LiFeAs, is studied by scanning tunneling
microscopy and spectroscopy. A gap map of the unreconstructed surface indicates
a high degree of homogeneity in this system. Spectra at 2 K show two nodeless
superconducting gaps with meV and
meV. The gaps close as the temperature is increased to the bulk
indicating that the surface accurately represents the bulk. A dip-hump
structure is observed below with an energy scale consistent with a
magnetic resonance recently reported by inelastic neutron scattering
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