Liquid Crystal Phases of Colloidal Mixtures of Ferromagnetic and Non-magnetic Nanoplates*

Colloidal nanoplates form liquid crystal phases at high concentrations driven by the Onsager excluded volume effect. For ferromagnetic nanoplates, where magnetic dipole-dipole interactions are present, a ferromagnetic nematic phase has been observed [Nat Comm, 7: 10394, 2016]. Here, we study liquid crystal phase behavior of colloidal mixtures of ferromagnetic barium hexaferrite and non-magnetic, exfoliated monolayer zirconium phosphate nanoplates. A series of phases, including a paramagnetic isotropic phase, a paramagnetic nematic, a paramagnetic glassy phase, a reentrant isotropic phase, and a ferromagnetic nematic are observed. All these phases show a strong response to applied magnetic fields. Synchrotron X-ray diffraction used to probe the order, with and without applied fields, shows evidence of local heterogeneous structures in the paramagnetic nematic phase.