Creating chiral superstructures in magnetic quadrupole fields.

i o f p o d l c a right-handed circularly polarized light. Another interesting property is optical rotatory dispersion under linearly polarized light excitation, resulting in continuous color-switching in a chiral medium. Driven by these remarkable properties, researchers have developed many methods to create chirality on achiral materials, such as templating methods, mechanical deformation and lithography [ 2 , 3 ]. DNA templates are widely used in this regard to assemble plasmonic nanoparticles into chiral superstructures [ 4 ]. Lithography is a top-down fabrication method for preparing chiral structures [ 5 ]. However, these existing methods only work for materials of specific shapes, chemical compositions or size ranges. Besides, the chiral structure formation is not reversible. Materials have fixed handedness once made and creating oppositely handed materials requires additional templates or fabrication. These challenges have remained for decades. A recent research article in Science reports a general assembly approach to chiral superstructures using quadrupole fields of permanent magnets [ 6 ]. This