Self-contained Kondo effect in single molecules

Kondo coupling of f and conduction electrons is a common feature of f -electron intermetallics. Similar effects should occur in carbon ring systems (metallocenes). Evidence for Kondo coupling in Ce(C8H8)2 (cerocene) and the ytterbocene Cp*2Yb(bipy) is reported from magnetic susceptibility and LIII-edge x-ray absorption spectroscopy. These well-defined systems provide a new way to study the Kondo effect on the nanoscale, should generate insight into the Anderson Lattice problem, and indicate the importance of this often-ignored contribution to bonding in organometallics. PACS numbers: 75.20.Hr, 71.27.+a Investigations into the Kondo effect, whereby a local magnetic moment spin-polarizes local conduction electrons forming a magnetic singlet, has recently broadened from the realm of understanding heavy-fermion, mixed valent and other related intermetallic alloys, to the study of transport and magnetic properties of quantum dots The main difference between the Kondo effect in a bulk system and a nanoparticle is one of quantum confinement, where the system is small enough that, at least in the absence of the Kondo effect, the conduction band is no longer continuous, instead forming a set of discrete states with energy gap