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

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 $\Phi/\Phi_0 = 1/2$, 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

Quenching of phase coherence in quasi-one dimensional ring crystals

The comparison of the single-particle (SP) dynamics between the whisker and ring NbSe$_3$ crystals provides new insight into the phase transition properties in quasi-one-dimensional charge density wave (CDW) systems.Comment: 9 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 $M/r \to 0$ (where $M$ is the black hole mass and $r$ 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.

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.

Gastro-intestinal parasites of pigs in Sardinia: a copromicroscopical investigation

This paper illustrates a copromicroscopical investigation carried out in Sardinia to update epidemiological data on diffusion of gastro-intestinal parasites in swine. Results obtained lead to suggest the employment of copromicroscopic exam to monitorate parasites diffusion in swine breedings in order to set up correct prophylactic and therapeutically intervents

Electronic Properties of Topological Materials: Optical Excitations in Moebius Conjugated Polymers

Electronic structures and optical excitations in Moebius conjugated polymers are studied theoretically. Periodic and Moebius boundary conditions are applied to the tight binding model of poly(para-phenylene), taking exciton effects into account. We discuss that oligomers with a few structural units are more effective than polymers for observations of effects of discrete wave numbers that are shifted by the change in boundary condition. Next, calculations of optical absorption spectra are reported. Certain components of optical absorption for an electric field perpendicular to the polymer axis mix with absorption spectra for an electric field parallel to the polymer axis. Therefore, the polarization dependences of an electric field of light enable us to detect whether conjugated polymers have the Moebius boundary.Comment: 10 pages, 6 figures, to be published in J. Phys. Soc. Jpn., Vol. 74 No. 2 (February, 2005), Letter sectio