Self-Assembled 2D Dipole Clusters made of Magnetic Particles: Experiment, Modeling, and Application for Tunable Photonic Crystals

Abstract

Two-dimensional magnetic dipole cluster is an interesting model system which shows an interplay between continuum and discrete descriptions. It has also potential in the context of tunable photonic crystals. In this work we study experimentally the static properties of confined ordered 2D magnetic clusters and the order-disorder transition in these clusters. We develop continuum model, similar to Thomas-Fermi model for atoms, which accounts fairly well for the smooth part of the dependence of static cluster properties on the number of particles [M. Golosovsky, Y. Saado, D. Davidov, Phys. Rev. E 65, 061405 (2002)]. However, on top of it we observe quasiperiodic fluctuations at “magic” numbers corresponding to particularly symmetric particle configurations. We demonstrate that these fluctuations arise from the discrete nature of clusters.