Condensed Matter Seminar: Currents and correlations in ionic systems

Determining the response of an electrolyte to an external field is a century-old non-equilibrium statistical physics problem. Its theoretical exploration started with the works of Debye and Hückel, and later of Onsager.

In this talk, we will examine temporal responses of ionic systems, subject to a quench of an external electric field. In particular, we study the response of the density-density correlation functions and induced electric currents. 

Leveraging Stochastic Density Functional Theory and integrating hydrodynamic interactions, we analyse the total electric current as a function of ionic density-density correlation functions. We show that the correlations do not follow the same trajectory when the field is switched on or off. Accordingly, the current decays exponentially when the field is switched off, yet it relaxes algebraically to its stationary value when the field is switched on, rooted in a non-linear effect. 

Moreover we demonstrate that the long range behavior of the correlations is dominated by an anisotropic diffusion process, which accounts for the algebraic decay of the currents.