936 research outputs found
Possible Excitonic Phase of Graphite in the Quantum Limit State
The in-plane resistivity, Hall resistivity and magnetization of graphite were
investigated in pulsed magnetic fields applied along the \textit{c}-axis. The
Hall resistivity approaches zero at around 53 T where the in-plane and
out-of-plane resistivities steeply decrease. The differential magnetization
also shows an anomaly at around this field with a similar amplitude compared to
that of de Haas-van Alphen oscillations at lower fields. This transition field
appears insensitive to disorder, but reduces with doping holes. These results
suggest the realization of the quantum limit states above 53 T. As a plausible
explanation for the observed gapped out-of-plane conduction above 53 T, the
emergence of the excitonic BCS-like state in graphite is proposed.Comment: 15 pages, 6 figures, to be published in J. Phys. Soc. Jp
Brain tumors induced in rats by human adenovirus type 12
Oncogenesis of human adenovirus type 12 in the brain
of rats was examined. Newborn rats of Sprague-Dawley and Donryu strains were injected intracranially with human adenovirus type 12. The incidence of intracranial tumors was 91% (30/33) in SpragueDawley and 56% (14/25) in Donryu rats. Except for one tumor nodule located in the parietal cortex of a Sprague.Dawley rat, all tumors developed in the paraventricular areas or in the meninges. Tumors
were quite similar histologically to those induced in hamsters and mice resembling the undifferentiated human brain tumors such as medulloblastoma, ependymoblastoma and embryonic gliomas. From the histological features and primary sites of tumor development, it is suggested that the tumors in the brain of rats induced by adenovirus
type 12 originate from the embryonic cells in the paraventricular area and also from the undifferentiated supporting cells of the peripheral nerves in the leptomeninges.</p
Magnetization Plateaus in the Spin-1/2 Kagome Antiferromagnets: Volborthite and Vesignieite
The magnetization of two spin-1/2 kagome antiferromagnets, volborthite and
vesignieite, has been measured in pulsed magnetic fields up to 68 T. A
magnetization plateau is observed for each compound near the highest magnetic
field. Magnetizations at saturation are approximately equal to 0.40Ms for both
compounds, where Ms is the fully saturated magnetization, irrespective of a
difference in the distortion of the kagome lattice between the two compounds.
It should be noted that these values of magnetizations are significantly larger
than Ms/3 predicted theoretically for the one-third magnetization plateau in
the spin-1/2 kagome antiferromagnet. The excess magnetization over Ms/3 is
nearly equal to the sum of the magnetizations gained at the second and third
magnetization steps in volborthite, suggesting that there is a common origin
for the excess magnetization and the magnetization steps.Comment: 4 pages, 4 figures. Phys. Rev. B, accepte
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