  A promising approach in designing composite materials with unusual physical
behavior combines solid nanostructures and orientationally ordered soft matter
at the mesoscale. Such composites not only inherit properties of their
constituents but also can exhibit emergent behavior, such as ferromagnetic
ordering of colloidal metal nanoparticles forming mesoscopic magnetization
domains when dispersed in a nematic liquid crystal. Here we demonstrate the
optical patterning of domain structures and topological defects in such
ferromagnetic liquid crystal colloids, which allows for altering their response
to magnetic fields. Our findings reveal the nature of the defects in this soft
matter system which is different as compared to non-polar nematics and
ferromagnets alike.

Soft Condensed Matter