Magnetically Driven Janus Micro-Ellipsoids Realized via Asymmetric Gathering of the Magnetic Charge

A simple and general method to realize Janus paramagnetic micro-ellipsoids is demonstrated. We elongate liquefied spherical paramagnetic particles embedded in a thermoplastic thin film upon application of a mechanical stress and gather the magnetic doping of the particles by using an external high magnetic field gradient. The asymmetric location of the nanoscale superparamagnetic grains inside the anisotropic particles is confirmed by TEM, and by following the particle dynamics under a rotating magnetic field.