Orateur
Description
The interplay of electron-electron interactions and strong disorder superconductor-insulator transition leads to the superconductor-insulator transition (SIT). Beginning with the pioneering experiment of Haviland et al. [1], this phenomenon has remained enigmatic. This begins with the question of what to call an insulator. Very early, scaling theories exploited a duality of Cooper-pairs and vortices in 2D films [2]. Within this picture, the dual of the superconducting state is a vortex superfluid that behaves electrically insulating. This scenario has led to an intense activity, centered around scaling behavior of resistance isotherms as function of a control parameter. In many cases, the temperature dependence of the resistance resembled more a metal with quantum corrections, however. Later, also highly insulating states have been found, e.g., in InOx, TiN, and NbN. Hopping conductance, thermally activated conductance and even finite temperature insulation were observed. Moreover, there can be intermediate metallic-like states, where the resistance eventually saturates as a function of temperature.
I will give an overview over these phenomena and discuss different avenues of their interpretation.
[1] D. B. Haviland, Y. Liu, A. M. Goldman, Phys. Rev. Lett. 62, 2180 (1989).
[2] M. P. A. Fisher, Phys. Rev. Lett. 65, 923 (1990).