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 $β$ of order unity. Here, $β= ω_c / ω_{pd}$ is the ratio of the cyclotron and plasma frequencies for dust particles. The mean-square displacement ${\rm {MSD}} = 4 D_αt^α$ is found to have an exponent $α> 1$, indicating superdiffusion, with $α$ increasing monotonically to $1.1$ as $β$ 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 $ω_{peak}$ that empirically obeys $ω_{peak}^2 = ω_c^2+ ω_{pd}^2/4$.