Self-Diffusion in a Spatially Modulated System of Electrons on Helium

Abstract

We present results of molecular dynamics simulations of the electron system on the surface of liquid helium. The simulations are done for 1600 electrons with periodic boundary conditions. Electron scattering by capillary waves and phonons in helium is explicitly taken into account. We find that the self-diffusion coefficient superlinearly decreases with the decreasing temperature. In the free electron system it turns to zero essentially discontinuously, which we associate with the liquid to solid transition.In contrast, when the system is placed in the fully commensurate one-dimensional potential the freezing of the diffusion occurs smoothly. We relate this change to the fact that, as we show, a Wigner crystal in such a potential is stable, in contrast to systems with a short-range inter-particle coupling. We find that the freezing temperature nonmonotonically depends on the commensurability parameter. We also find incommensurability solitons in the solid phase. The results reveal peculiar features of the dynamics of a strongly correlated system with long-range coupling placed into a periodic potential. 1

Wigner crystal diode

“…However, this work was focused on analysis of specific physical effects related to diode transport for which it was sufficient to stay within a maximal N tot = 445 (see below). Recently, the numerical simulations of 2D Wigner crystal in a spatially modulated system with up to 1600 charges has been reported in [50]. However, the possible links with the Aubry transition have been not discussed in this work.…”

Many-electron system on helium and the color center spectroscopy

“…On the time scale much longer than ω c /ω 2 p , if electrons form a liquid, they are diffusing. Self-diffusion involves correlated many-electron motion, as seen in the simulations [41]. Therefore it is reasonable to assume that the distribution of the diffusion trajectories is Gaussian.…”

Thermoelectric properties of Wigner crystal in two-dimensional periodic potential

“…We note that the self-diffusion of electrons in 2D periodic potential had been discussed recently in [36] but thermoelectricity and the Aubry pinned phase had not been analyzed there.…”