Exact Calculation of the Vortex-Antivortex Interaction Energy in the Anisotropic 3D XY-model

We have developed an exact method to calculate the vortex-antivortex interaction energy in the anisotropic 3D-XY model. For this calculation, dual transformation which is already known for the 2D XY-model was extended. We found an explicit form of this interaction energy as a function of the anisotropic ratio and the separation $r$ between the vortex and antivortex located on the same layer. The form of interaction energy is $\ln r$ at the small $r$ limi t but is proportional to $r$ at the opposite limit. This form of interaction energ y is consistent with the upper bound calculation using the variational method by Cataudella and Minnhagen.Comment: REVTeX 12 pages, In print for publication in Phys. Rev.

Non linear excess conductivity of Bi2_2Sr2_2Can−1_{n-1}Cun_nO2n+4+x_{2n+4+x} (n = 1,2), thin films

The suppression of excess conductivity with electric field is studied for Bi$_2$Sr$_2$Ca$_{n-1}$Cu$_n$O$_{2n+4+x}$ ($n$ = 1, 2) thin films. A pulse-probe technique is used, which allows for an estimate of the sample temperature. The characteristic electric field for fluctuations suppression is found well below the expected value for all samples. For the $n=1$ material, a scaling of the excess conductivity with electric field and temperature is obtained, similar to the scaling under strong magnetic field

Critical fluctuation conductivity in layered superconductors in strong electric field

The paraconductivity, originating from critical superconducting order-parameter fluctuations in the vicinity of the critical temperature in a layered superconductor is calculated in the frame of the self-consistent Hartree approximation, for an arbitrarily strong electric field and zero magnetic field. The paraconductivity diverges less steep towards the critical temperature in the Hartree approximation than in the Gaussian one and it shows a distinctly enhanced variation with the electric field. Our results indicate that high electric fields can be effectively used to suppress order-parameter fluctuations in high-temperature superconductors.Comment: 11 pages, 2 figures, to be published in Phys. Rev.

Variable-range-hopping-like transverse conductivity of the quasi one-dimensional conductor TaS3_{3}

We report temperature dependence of transverse conductivity and its hysteresis in TaS$_3$. The results argue that the conductivity mechanism is variable-range hopping (VRH)

On the critical current for the charge density wave transport

We report transport measurements under very high current densities $j$, up to $10^8$ A/cm$^2$, of quasi-one-dimensional charge-density wave (CDW) conductors NbSe$_3$ and TaS$_3$. Above $j_0-10^1$ A/cm$^2$ the point contacts NbSe$_3$-NbSe$_3$ show a sharp singularity, and the TaS$_3$ nanosamples show metallic temperature dependence (positive d$R$/d$n$. We interpret both results as an evidence for the suppression of the Peierls gap 2A and development of the metallic state above $j_0$. Possible scenarios of the Peierls state destruction are discussed

The In-plane anisotropy of the hall anomaly in BSCCO whiskers

The Hall effect in single crystal BSCCO whiskers has been measured, with the current flowing along the a and b crystallographic directions. The ab-plane anisotropy of the Hall anomaly is found. The magnitude of the anomaly, as well as its anisotropy, are strongly affected by the structural defects. © 2005 Springer Science+Business Media, Inc