9,631 research outputs found
Charge states and magnetic ordering in LaMnO3/SrTiO3 superlattices
We investigated the magnetic and optical properties of
[(LaMnO3)n/(SrTiO3)8]20 (n = 1, 2, and 8) superlattices grown by pulsed laser
deposition. We found a weak ferromagnetic and semiconducting state developed in
all superlattices. An analysis of the optical conductivity showed that the
LaMnO3 layers in the superlattices were slightly doped. The amount of doping
was almost identical regardless of the LaMnO3 layer thickness up to eight unit
cells, suggesting that the effect is not limited to the interface. On the other
hand, the magnetic ordering became less stable as the LaMnO3 layer thickness
decreased, probably due to a dimensional effect.Comment: 17 pages including 4 figures, accepted for publication in Phys. Rev.
Evidence of metallic clustering in annealed Ga1-xMnxAs from atypical scaling behavior of the anomalous Hall coefficient
We report on the anomalous Hall coefficient and longitudinal resistivity
scaling relationships on a series of annealed Ga1-xMnxAs epilayers (x~0.055).
As-grown samples exhibit scaling parameter n of ~ 1. Near the optimal annealing
temperature, we find n ~ 2 to be consistent with recent theories on the
intrinsic origins of anomalous Hall Effect in Ga1-xMnxAs. For annealing
temperatures far above the optimum, we note n > 3, similar behavior to certain
inhomogeneous systems. This observation of atypical behavior agrees well with
characteristic features attributable to spherical resonance from metallic
inclusions from optical spectroscopy measurements.Comment: 3 pages, 3 figure
Effects of pressure on the ferromagnetic state of the CDW compound SmNiC2
We report the pressure response of charge-density-wave (CDW) and
ferromagnetic (FM) phases of the rare-earth intermetallic SmNiC2 up to 5.5 GPa.
The CDW transition temperature (T_{CDW}), which is reflected as a sharp
inflection in the electrical resistivity, is almost independent of pressure up
to 2.18 GPa but is strongly enhanced at higher pressures, increasing from 155.7
K at 2.2 GPa to 279.3 K at 5.5 GPa. Commensurate with the sharp increase in
T_{CDW}, the first-order FM phase transition, which decreases with applied
pressure, bifurcates into the upper (T_{M1}) and lower (T_c) phase transitions
and the lower transition changes its nature to second order above 2.18 GPa.
Enhancement both in the residual resistivity and the Fermi-liquid T^2
coefficient A near 3.8 GPa suggests abundant magnetic quantum fluctuations that
arise from the possible presence of a FM quantum critical point.Comment: 5 pages, 5 figure
Interplay between carrier and impurity concentrations in annealed GaMnAs intrinsic anomalous Hall Effect
Investigating the scaling behavior of annealed GaMnAs anomalous
Hall coefficients, we note a universal crossover regime where the scaling
behavior changes from quadratic to linear, attributed to the anomalous Hall
Effect intrinsic and extrinsic origins, respectively. Furthermore, measured
anomalous Hall conductivities when properly scaled by carrier concentration
remain constant, equal to theoretically predicated values, spanning nearly a
decade in conductivity as well as over 100 K in T. Both the qualitative
and quantitative agreement confirms the validity of new equations of motion
including the Berry phase contributions as well as tunablility of the intrinsic
anomalous Hall Effect.Comment: 4 pages, 5 figure
Ground-state electric quadrupole moment of 31Al
Ground-state electric quadrupole moment of 31Al (I =5/2+, T_1/2 = 644(25) ms)
has been measured by means of the beta-NMR spectroscopy using a spin-polarized
31Al beam produced in the projectile fragmentation reaction. The obtained Q
moment, |Q_exp(31Al)| = 112(32)emb, are in agreement with conventional shell
model calculations within the sd valence space. Previous result on the magnetic
moment also supports the validity of the sd model in this isotope, and thus it
is concluded that 31Al is located outside of the island of inversion.Comment: 5 page
Microstructure, Mechanical Property and Biocompatibility of Porous Ti-Nb-Zr Alloys Fabricated by Rapid Sintering using Space Holder
Space holder method can easily control Young’s modulus due to control the pore size, distribution and shape. In this study, porous Ti-Nb-Zr biomaterial which is not included poison elements was successfully fabricated by powder metallurgy using space holder of NH4HCO3 and foaming agent of TiH2. The consolidation of powder was conducted by spark plasma sintering process (SPS) at 850 °C under 30MPa conditions. The effect of space holder contents on pore size and distribution of Ti-Nb-Zr alloys was observed by optical microscope (OM) and scanning electron microscope (SEM). As a result of microstructure observation, a lot of pore was uniformly distributed in the sintered Ti-Nb-Zr alloys. Cell cultivation experiments were conducted using cell cultivation experimental. The porous Ti-Nb-Zr alloys were fabricated successfully with 30% pore ratio and 50-60GPa of Young’s modulus. Biocompatibility of porous Ti-Nb-Zr alloys is similar to Ti-6Al-4V alloy
Aqueous solution dispersement of carbon nanotubes
Carbon nanotubes (CNTs) are dispersed in an aqueous buffer solution consisting of at least 50 weight percent water and a remainder weight percent that includes a buffer material. The buffer material has a molecular structure defined by a first end, a second end, and a middle disposed between the first and second ends. The first end is a cyclic ring with nitrogen and oxygen heteroatomes, the middle is a hydrophobic alkyl chain, and the second end is a charged group
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