  In complex colloidal systems, interparticle interactions strongly affect the
dynamics of the constituting particles. A study of the dynamical response also
provides invaluable information on the character of those interactions. Here we
demonstrate how tuning the electrostatic interactions by an ionic surfactant in
dispersions of magnetic nanoplatelets leads to developing new dynamic modes in
magnetic response spectra. The collective modes can be induced or suppressed by
either varying the concentration ratio of the magnetic nanoplatelets (MP) to
the surfactant or increasing the MP concentration reflecting the nanoscale
characteristics of this fluid magnet.
