Nonequilibrium orientational bistability of a magnetically-driven slender particle

Abstract

Externally driven systems are non-equilibrium but accessible to stationary states. By combining theoretical calculations and particle-based simulations, we investigate the orientational configuration of a transversely-magnetized slender particle in a rotating magnetic field. Our results reveal nonequilibrium orientational bistability in both regimes that the particle rotates synchronously and asynchronously with the field. The relative populations of standing and lying orientations depend strongly on the driving frequency in the synchronous regime, whereas they are primarily controlled by the magnetic field strength in the asynchronous regime. Effective free-energy approximations further capture the principal features of the steady-state orientational distributions in both regimes. Our work aims to give a statistical-thermodynamic description of orientational bistability in magnetically-driven slender particles, paving the way for relevant experimental designs and advanced applications.