Crystallization in mass and charge asymmetric bilayers

We consider Coulomb crystal formation in quantum electron-ion (hole) bilayers. Varying the mass ratio $M$ of ions and electrons between 1 and 100 for a fixed layer separation $d$ at low temperature and high density, one can tune the hole behavior from delocalized (quantum) to localized (quasi-classical) while the electrons remain delocalized all the time. While in 3D plasmas [1], ions crystallize if the mass ratio exceeds a critical value of $M_{cr} \sim 80$, in bilayers $M_{cr}$ can be drastically reduced by properly choosing $d$ and the in-layer particle density. The complicated overlap of correlation and quantum effects of both, electrons and holes, is fully taken care of by performing first-principle path integral Monte Carlo simulations. \newline [1] M. Bonitz, V.S. Filinov, V.E. Fortov. P.R. Levashov, and H. Fehske, Phys. Rev. Lett. 95, 235006 (2005) and J. Phys. A: Math. Gen. {\bf 39}, 4717 (2006). [2] P. Ludwig, A. Filinov, Yu. Lozovik, H. Stolz, and M. Bonitz, Crystallization in mass-asymmetric electron-hole bilayers, Contrib. Plasma Phys. (2007), ArXiv: cond-mat/0611556