Anisotropic self-assembly of soft particles induced by elliptically polarized AC electric fields

Attractive dipole interactions can be induced between equally charged soft nanoparticles under the influence of AC electric fields. The combination of charge repulsion and dipole attraction, along with different screening responses from an underlying electrolyte, leads to complex aggregations ranging from chain-like formation for linear polarizations to isotropic planar structures in the case of circular polarizations. In this work, we analyze the role of varying field anisotropies in these self-assembled structures. To this end, the formalism previously developed for the coarse-grained interactions of soft particles in the presence of linear [T. Colla et al., ACS Nano 12, 4321–4337 (2018)] and circular [M. Reich et al., Soft Matter 21, 1516–1528 (2025)] field polarizations is naturally extended to incorporate elliptical polarizations of arbitrary asymmetries. A rich variety of self-assembly formations is found at intermediate field anisotropies, thus bridging the gap between linear- and circular-field-induced self-assembly scenarios.