1,526 research outputs found
Anomalous phase shift in a twisted quantum loop
Coherent motion of electrons in a twisted quantum ring is considered to
explore the effect of torsion inherent to the ring. Internal torsion of the
ring composed of helical atomic configuration yields a non-trivial quantum
phase shift in the electrons' eigenstates. This torsion-induced phase shift
causes novel kinds of persistent current flow and an Aharonov-Bohm like
conductance oscillation. The two phenomena can occur even when no magnetic flux
penetrates inside the twisted ring, thus being in complete contrast with the
counterparts observed in untwisted rings.Comment: 13 paes, 5 figure
Spin-Glass-like Transition and Hall Resistivity of Y2-xBixIr2O7
Various physical properties of the pyrochlore oxide Y2-xBixIr2O7 have been
studied. The magnetizations M measured under the conditions of the
zero-field-cooling(ZFC) and the field-cooling(FC) have different values below
the temperature T=TG. The anomalous T-dependence of the electrical
resistivities r and the thermoelectric powers S observed at around TG indicates
that the behavior of the magnetization is due to the transition to the state
with the spin freezing. In this spin-frozen state, the Hall resistivities rH
measured with the ZFC and FC conditions are found to have different values,
too, in the low temperature phase (T<TG). Possible mechanisms which induce such
the hysteretic behavior are discussed.Comment: 9 pages, 7 figures, J. Phys. Soc. Jpn. 72 (2003) No.
Torsion-induced persistent current in a twisted quantum ring
We describe the effects of geometric torsion on the coherent motion of
electrons along a thin twisted quantum ring. The geometric torsion inherent in
the quantum ring triggers a quantum phase shift in the electrons' eigenstates,
thereby resulting in a torsion-induced persistent current that flows along the
twisted quantum ring. The physical conditions required for detecting the
current flow are discussed.Comment: 9 pages, 3 figure
High sensitive X-ray films to detect electron showers in 100 GeV region
Nonscreen type X-ray films were used in emulsion chamber experiments to detect high energy showers in cosmic rays. Ranges of the detection threshold is from about 1 to 2 TeV depending on the exposure conditions. Different types of X-ray films and sheets i.e. high sensitive screen type X-ray films and luminescence sheets were tested. The threshold of the shower detection is found to be about 200 GeV, which is much lower than that of nonscreen type X-ray films. These films are useful to detect showers in the medium energy range, a few hundred GeV, of the cosmic ray electrons
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