[Back]

M. Antlanger, G. Kahl, M. Mazars, L. Samaj, E. Trizac:
"The polymorphic plethora of Wigner bilayer systems";
Poster: 10th Liquid Matter Conference (2017), Ljubljana; 07-17-2017 - 07-21-2017; in: "Liquids 2017 10TH LIQUID MATTER CONFERENCE", (2017), 1.009.

We consider an ensemble of mobile point charges (nominal charges -e), immersed in a dielectric medium and confined between two parallel plates, which are separated by a distance η and which bear uniform charge densities σ1e and σ2e, with the asymmetry parameter A=σ2/σ1. Combining complementary theoretical approaches (i.e., analytical
calculations, numerical optimization techniques based on evolutionary algorithms) we provide at vanishing temperature a comprehensive diagram of ordered ground state configurations of the charges as we systematically vary the asymmetry parameter A and the plate separation η [1]. The complex interplay between commensurability requirements between the ordered structures on each of the layers, on one side, and the quest for local charge neutralization, on the other side, leads to a plethora of exotic Wigner bilayer configurations: among those are Archimedean tilings or pentagonal structures, both of which can be considered as precursors of quasi-crystalline structures. Complementary Monte Carlo simulations, carried out at small, but finite temperatures provide evidence of the thermal stability of the predicted structures. In addition, the system comes up with other unexpected features, such as long-range attractions between the plates, the appearance of macroscopic charges, or the emergence of non-conventional phase transitions, pertaining to different universality classes. Our investigations demonstrate that even in a simple system the emergence of complex structures can easily be triggered via a systematic variation of two external parameters (in our case A and η).

[1] M. Antlanger, G. Kahl, M. Mazars, L. Samaj, and E. Trizac, Phys. Rev. Lett. 117,
118002 (2016).

http://publik.tuwien.ac.at/files/publik_266973.pdf

Project Head Gerhard Kahl:
DFS