We report direct observation of magnetochiral (MCh) effects for the $X$-band microwaves through a single metamolecule consisting of a copper chiral structure and ferrite rod. A fictitious interaction between chirality and magnetism is realized in the metamolecule without intrinsic electronic interactions. The MCh effects are induced at the resonant optical activities by applying a weak dc magnetic field of 1 mT, and are increased with the magnetic field. The nonreciprocal differences in refractive indices are evaluated to be ${10}^{-3}$ at 200 mT.

• Received 8 June 2014

DOI:https://doi.org/10.1103/PhysRevLett.113.235501