C. Rossel | Searcharxiv

arXiv2001

Electrical current distribution across a metal-insulator-metal structure during bistable switching

Combining scanning electron microscopy (SEM) and electron-beam-induced current (EBIC) imaging with transport measurements, it is shown that the current flowing across a two-terminal oxide-based capacitor-like structure is preferentially confined in areas localized at defects. As the thin-film device switches between two different resistance states, the distribution and intensity of the current paths, appearing as bright spots, change. This implies that switching and memory effects are mainly determined by the conducting properties along such paths. A model based on the storage and release of charge carriers within the insulator seems adequate to explain the observed memory effect.

cond-mat.mtrl-sci↗

arXiv1994

Comment on "Evolution from BCS Superconductivity to Bose-Einstein Condensation: Role of the Parameter $k_{\rm F} ξ$ in Interpreting the Experimental Plot by Uemura et al.''}

The problem of crossover from BCS to Bose-Einstein condensation has recently attracted considerable interest owing to the discovery of high-$T_{\rm c}$ cuprates. Their short coherence length, $ξ$, places these materials in the interesting region between BCS and Bose-Einstein condensation. In the paper of F. Pistolesi and G.C. Strinati (Phys. Rev. B {\bf 49}, 6356 (1994)), the Nozières and Schmitt-Rink approach (NSR) is taken, which is valid for the weak coupling regime. They derive a relation between $T_{\rm c}$ and $T_{\rm F}$, which they insist is valid for any coupling strength. We present arguments that their assumptions are incorrect by using our fully self-consistent T-matrix formalism in two dimensions, and show that the NSR approach produces unphysical results in this case.

cond-mat↗