Cage correlation and diffusion in strongly coupled three-dimensional Yukawa systems in magnetic fields

Abstract

The influence of an external homogeneous magnetic field on the quasilocalization of the particles-characterized quantitatively by cage correlation functions-in strongly coupled three-dimensional Yukawa systems is investigated via molecular dynamics computer simulations over a wide domain of the system parameters (coupling and screening strengths, and magnetic field). The caging time is found to be enhanced by the magnetic field B. The anisotropic migration of the particles in the presence of magnetic field is quantified via computing directional correlation functions, which indicate a more significant increase of localization in the direction perpendicular to B, while a moderate increase is also found along the B field lines. Associating the particles' escapes from the cages with jumps of a characteristic length, a connection is found with the diffusion process: the diffusion coefficients derived from the decay time of the directional correlation functions in both the directions perpendicular to and parallel with B are in very good agreement with respective diffusion coefficients values obtained from their usual computation based on the mean-squared displacement of the particles.

Transport regimes spanning magnetization-coupling phase space

“…Panels g and h show that at high Γ strong magnetization further exaggerates features of the velocity autocorrelation function normally associated with Coulomb coupling, such as the large negative correlation at early times. Previous theories have discussed velocity caging by strong magnetization at weak coupling [26,28], and similar features of the velocity autocorrelation function have been observed in previous MD simulations at strong coupling [9,44,49]. Features associated with the oscillation spectrum at strong coupling have also been observed in MD simulations [50].…”

Effect of magnetic field and friction force on the velocity autocorrelation in two‐dimensional Yukawa liquids

“…The latter was found to increase the particle localization time (i.e. the efficiency of “caging”), as revealed by molecular dynamics simulations . In a laboratory dusty plasma, the amplification of an external magnetic field was found to lead to the destruction of ordered structures, owing to its influence on important parameters such as the charge of dust particles.…”

Self-diffusion in two-dimensional quasimagnetized rotating dusty plasmas

“…Our numerical simulations are directly motivated by previous numerical studies of diffusion in magnetized 3D Yukawa systems [19,39], studies on the connection between caging and diffusion in 2D Yukawa systems [40], and studies that identify superdiffusion in 2D magnetized systems [12,41]. Earlier investigations of non-magnetized Yukawa systems [33,[42][43][44][45][46] provide valuable references for the methodology, the possible presence of superdiffusion, and numerical data.…”