Speaker
Description
The fundamental properties of superfluids and superconductors are determined by the spatial coherence of the macroscopic condensate. Its fluctuations are pivotal to supercurrent flow, the functionality of superconducting nanostructures, and the response superconducting matter shows to magnetic fields. Central to a theoretical description is the coherence length which sets the relevant length scales of fluctuation effects. While a microscopic link is well established in weak-coupling BCS theory and Eliashberg-theory, it is a generally unknown quantity in strongly correlated superconductors where spatiotemporal fluctuations influence the critical temperature [1] and might underlie light-induced enhancement of superconductivity [2].
Here, we establish a link to directly calculate the coherence length as well as depairing currents and critical fields for superconductors with strong electron correlations from microscopic theories and first principles. We illustrate with the example of Alkali-doped fullerides (A$_3$C$_{60}$) how proximity of superconducting and Mott-localized states impact superconducting coherence, pairing localization, and critical temperature.
[1] Emery & Kivelson, Nature 374 (1995)
[2] Fausti et al., Science 331 (2011); Mitrano et al., Nature 530 (2016)
