Superdiffusion of 2D Yukawa liquids due to a perpendicular magnetic field

Abstract

Stochastic transport of a two-dimensional (2D) dusty plasma liquid with a perpendicular magnetic field is studied. Superdiffusion, which is a type of non-Fickian transport, is found to occur especially at higher magnetic fields with ${\hat{I}}^2$ of order unity. Here, ${\hat{I}}^2=\ddot{I}{‰}_c/\ddot{I}{‰}_{pd}$ is the ratio of the cyclotron and plasma frequencies for dust particles. The mean-square displacement $\mathrm{MSD}=4D_{\hat{I}}\pm t^{\hat{I}}\pm$ is found to have an exponent $\hat{I}\pm >1$, indicating superdiffusion, with $\hat{I}\pm$ increasing monotonically to $1.1$ as ${\hat{I}}^2$ increases to unity. The 2D Langevin molecular dynamics simulation used here also reveals that another indicator of random particle motion, the velocity autocorrelation function (VACF), has a dominant peak frequency $\ddot{I}{‰}_{peak}$ that empirically obeys $\ddot{I}{‰}_{peak}^2=\ddot{I}{‰}_c^2+\ddot{I}{‰}_{pd}^2/4$.

8 pages text, 6 figures