88 research outputs found
Analysis of the Demagnetization Process of Nd-Fe-B Sintered Magnets at Elevated Temperatures by Magnetic Domain Observation Using a Kerr Microscope
Magnetization reversal and its propagation in sintered Nd–Fe–B magnets were clearly observed at elevated temperatures up to 150 °C using a Kerr microscope, image processing, and photo editing. Simultaneous magnetization reversal in several grains along the easy axis direction occurred at elevated temperature, and the extent of simultaneous magnetization reversal increased with temperature. This indicates that reduction in the coercivity of Nd–Fe–B sintered magnets at elevated temperatures is attributable to decrease in anisotropy and insufficient pinning of domain walls at grain boundaries
Novel Orbital Ordering induced by Anisotropic Stress in a Manganite Thin Film
We performed resonant and nonresonant x-ray diffraction studies of a
Nd0.5Sr0.5MnO3 thin film that exhibits a clear first-order transition. Lattice
parameters vary drastically at the metal-insulator transition at 170K (=T_MI),
and superlattice reflections appear below 140K (=T_CO). The electronic
structure between T_MI and T_CO is identified as A-type antiferromagnetic with
the d_{x2-y2} ferroorbital ordering. Below T_CO, a new type of antiferroorbital
ordering emerges. The accommodation of the large lattice distortion at the
first-order phase transition and the appearance of the novel orbital ordering
are brought about by the anisotropy in the substrate, a new parameter for the
phase control.Comment: 4pages, 4figure
Orbital Ordering Structures in (Nd,Pr)0.5Sr0.5MnO3 Manganite Thin Films on Perovskite (011) Substrates
Structural study of orbital-ordered manganite thin films has been conducted
using synchrotron radiation, and a ground state electronic phase diagram is
made. The lattice parameters of four manganite thin films, Nd0.5Sr0.5MnO3
(NSMO) or Pr0.5Sr0.5MnO3 (PSMO) on (011) surfaces of SrTiO3 (STO) or
[(LaAlO3){0.3}(SrAl0.5Ta0.5O3){0.7}] (LSAT), were measured as a function of
temperature. The result shows, as expected based on previous knowledge of bulk
materials, that the films' resistivity is closely related to their structures.
Observed superlattice reflections indicate that NSMO thin films have an
antiferro-orbital-ordered phase as their low-temperature phase while PSMO film
on LSAT has a ferro-orbital-ordered phase, and that on STO has no
orbital-ordered phase. A metallic ground state was observed only in films
having a narrow region of A-site ion radius, while larger ions favor
ferro-orbital-ordered structure and smaller ions stabilize
antiferro-orbital-ordered structure. The key to the orbital-ordering transition
in (011) film is found to be the in-plane displacement along [0-1 1] direction.Comment: 19pages, 11 figure
Size of Orbital Ordering Domain Controlled by the Itinerancy of the 3d Electrons in a Manganite Thin Film
An electronic effect on a macroscopic domain structure is found in a strongly
correlated half-doped manganite film NdSrMnO3 grown on a (011)
surface of SrTiO3. The sample has a high-temperature (HT) phase free from
distortion above 180K and two low-temperature (LT) phases with a large
shear-mode strain and a concomitant twin structure. One LT phase has a large
itinerancy (A-type), and the other has a small itinerancy (CE-type), while the
lattice distortions they cause are almost equal. Our x ray diffraction
measurement shows that the domain size of the LT phase made by the HT-CE
transition is much smaller than that by the HT-A transition, indicating that
the difference in domain size is caused by the electronic states of the LT
phases.Comment: 9 pages, 4 figure
Telerobotics test bed for space structure assembly
A cooperative research on super long distance space telerobotics is now in progress both in Japan and USA. In this program. several key features will be tested, which can be applicable to the control of space robots as well as to terrestrial robots. Local (control) and remote (work) sites will be shared between Electrotechnical Lab (ETL) of MITI in Japan and Jet Propulsion Lab (JPL) in USA. The details of a test bed for this international program are discussed in this report
High magnetic field transport measurement of charge-ordered PrCaMnO strained thin films
We have investigated the magnetic-field-induced phase transition of
charge-ordered (CO) PrCaMnO thin films, deposited onto
(100)-oriented LaAlO and (100)-oriented SrTiO substrates using the
pulsed laser deposition technique, by measuring the transport properties with
magnetic fields up to 22T. The transition to a metallic state is observed on
both substrates by application of a critical magnetic field ( at 60K).
The value of the field required to destroy the charge-ordered insulating state,
lower than the bulk compound, depends on both the substrate and the thickness
of the film. The difference of the critical magnetic field between the films
and the bulk material is explained by the difference of in-plane parameters at
low temperature (below the CO transition). Finally, these results confirm that
the robustness of the CO state, depends mainly on the stress induced by the
difference in the thermal dilatations between the film and the substrate.Comment: 10 pages, 6 figures. To be published in Phys. Rev.
Liver cancer risk, coffee, and hepatitis C virus infection: a nested case–control study in Japan
We examined hepatocellular carcinoma mortality in relation to coffee consumption and anti-hepatitis C virus (HCV) antibody seropositivity in a nested case–control study involving 96 cases. The multivariate-adjusted odds ratios (95% confidence interval) for daily coffee drinkers vs non-drinkers were 0.49 (0.25–0.96), 0.31 (0.11–0.85), and 0.75 (0.29–1.92) in all cases, in HCV-positive and in HCV-negative individuals, respectively
The effect of interaction between hepatitis C virus and cigarette smoking on the risk of hepatocellular carcinoma
We evaluated the interaction between hepatitis C virus (HCV) and cigarette smoking on death from hepatocellular cancer in The Japan Collaborative Cohort Study. The odds ratio of death from HCC for smoking was 9.60 (1.50–61.35) and 1.71(0.58–5.08) among anti-HCV positive and negative individuals, respectively
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