740 research outputs found
Quenching of phase coherence in quasi-one dimensional ring crystals
The comparison of the single-particle (SP) dynamics between the whisker and
ring NbSe crystals provides new insight into the phase transition
properties in quasi-one-dimensional charge density wave (CDW) systems.Comment: 9 pages, 4 figure
Duality Breaking of Vortex Configuration in a Hierarchical Honeycomb Network
We report measurements of Little-Parks oscillation on the hierarchical
honeycomb-superconducting network for investigating possible effects of
hierarchical structure in terms of spatial symmetry, parity and duality. We
observed an asymmetric Little-Parks oscillation about ,
although spatial symmetry was kept in the network. In comparison with a regular
honeycomb network, the asymmetric oscillation is attributed to hierarchy which
induces mixture of commensurate and incommensurate regions. The asymmetric
oscillation is found to indicate breaking of the duality of vortex
configuration.Comment: 12 pages, 6 figure
Aharonov-Bohm Effect at liquid-nitrogen temperature: Frohlich superconducting quantum device
The Aharonov-Bohm (AB) effect has been accepted and has promoted
interdisciplinary scientific activities in modern physics. To observe the AB
effect in condensed matter physics, the whole system needs to maintain phase
coherence, in a tiny ring of the diameter 1 micrometer and at low temperatures
below 1 K. We report that AB oscillations have been measured at high
temperature 79 K by use of charge-density wave (CDW) loops in TaS3 ring
crystals. CDW condensate maintained macroscopic quantum coherence, which
extended over the ring circumference 85 micrometer. The periodicity of the
oscillations is h/2e in accuracy within a 10 percent range. The observation of
the CDW AB effect implies Frohlich superconductivity in terms of macroscopic
coherence and will provide a novel quantum interference device running at room
temperature.Comment: 11 pages, 4 figure
Topologically Linked Crystals
We discovered a new class of topological crystals, namely linked rings of
crystals. Two rings of tantalum triselenide (TaSe3) single crystals were linked
to each other while crystal growing. The topology of the crystal form is called
a "Hopf link", which is the simplest link involving just two component unknots
linked together exactly once. The feature of the crystals is not covered by the
conventional crystallography.Comment: 6 pages, 3 figures, to appear in J. Crystal Growt
Does a black hole rotate in Chern-Simons modified gravity?
Rotating black hole solutions in the (3+1)-dimensional Chern-Simons modified
gravity theory are discussed by taking account of perturbation around the
Schwarzschild solution. The zenith-angle dependence of a metric function
related to the frame-dragging effect is determined from a constraint equation
independently of a choice of the embedding coordinate. We find that at least
within the framework of the first-order perturbation method, the black hole
cannot rotate for finite black hole mass if the embedding coordinate is taken
to be a timelike vector. However, the rotation can be permitted in the limit of
(where is the black hole mass and is the radius). For a
spacelike vector, the rotation can also be permitted for any value of the black
hole mass.Comment: 4 pages, Accepted for publication in Phys. Rev.
Domain-wall structure of a classical Heisenberg ferromagnet on a Mobius strip
We study theoretically the structure of domain walls in ferromagnetic states
on Mobius strips. A two-dimensional classical Heisenberg ferromagnet with
single-site anisotropy is treated within a mean-field approximation by taking
into account the boundary condition to realize the Mobius geometry. It is found
that two types of domain walls can be formed, namely, parallel or perpendicular
to the circumference, and that the relative stability of these domain walls is
sensitive to the change in temperature and an applied magnetic field. The
magnetization has a discontinuity as a function of temperature and the external
field.Comment: 7 pages, 10 figures; published versio
Possibility of Macroscopic resonant Tunneling near the Superconductor- Insulator Transition in YBaCuO Thin Films
Experimental results of I-V characteristics near the superconductor-insulator
transition observed for disorder-tuned YBaCuO thinfilms are presented. The I-V
characteristics exibit new quasiperiodic structures as a function of the
current. The current interval, the number of the dI/dV peaks, and the magnetic
field dependence of the peaks are consistent with the theoretical predictions
of the resonant tunneling of a phase particle ina tilted-cosine potential for
asingle Josephson junction with small capacitance.Comment: 7 pages, 4 figures, in press (Europhys. Lett.
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