Direct observation of magnetochiral effects through a single metamolecule in microwave regions.

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.