arXiv subjects

I. Sfar

Publications and source records attributed to I. Sfar.

4 recordsLinked to original sources

arXiv2007

Role of the cooling rate in the stability of the superconducting phase of (TMTSF)_2ClO_4

The noncentrosymmetric ClO$_4$ anions of the organic superconductor (TMTSF)$_2$ClO$_4$ order below 24K. The size of domains where the anions are ordered is substantially dependent on the cooling rate which is a key parameter for the stability of the low temperature electronic ground states. We study the effect of the cooling rate on the SC phase within a self consistent approach in the framework of the time dependent Ginzburg-Landau theory taking into account the superconducting fluctuations. We derive the superconducting transition temperature which is found to decrease with increasing cooling rate in agreement with recent experimental data.

cond-mat.supr-con↗

arXiv2006

Upper critical field from normal state fluctuations in Bi$_2$Sr$_2$CuO$_{6+δ}$

The in-plane magnetoresistance of an epitaxial Bi$_2$Sr$_2$CuO$_{6+δ}$ thin film was systematically investigated as a function of doping, above $T_c$. The orbital magnetoconductance is used to extract the crossover field line $H_{c2}^*(T)$ in the fluctuation regime. This field is found in good agreement with the upper critical field obtained from resistivity data below $T_c$, and exhibits a similar upward curvature, thus pointing toward the existence of a critical correlation length. The consequences regarding the nature of the resistive transition are discussed.

cond-mat.supr-con↗

arXiv2005

Current dependent fluctuations in a Bi$_2$Sr$_2$CuO$_{6+δ}$ thin film

The current dependence of the excess conductivity is measured up to $\simeq 3 T_c$ for a Bi$_2$Sr$_2$CuO$_{6+δ}$ thin film, as a function of doping. It is found to be anomalously sensitive to the transport current and to behave as a universal function of $T/T_c$ in the whole doping range. We discuss these results in the perspective of a granular superconductor with a gapless-like behavior.

cond-mat.supr-con↗

arXiv2004

Non linear excess conductivity of Bi$_2$Sr$_2$Ca$_{n-1}$Cu$_n$O$_{2n+4+x}$ (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.

cond-mat.supr-con↗