Organic magnetic materials studied by positive muons

Positive muons can be implanted into organic and molecular magnets in order to study their internal magnetic field distribution and any associated dyn amics. The muon behaves essentially as a "microscopic magnetometer", sensit ive to local magnetic order and magnetic fluctuations. We describe some rec ent experiments using this technique which were performed on a variety of o rganic systems, including nitronyl nitroxide magnets and materials with spi n-Peierls ground states, MF-M(TCNQ)(2) and DEM(TCNQ)(2), and demonstrate ho w the technique can give information concerning their ground states.