Magnetic Field Control of the Current through Molecular Ring Junctions

Whereas conducting loops are, in principle, sensitive to external magnetic field, as is pronouncedly exem- plified by the AharonovBohm (AB) effect, the small radius of molecular rings makes the observation of such effects challen- ging. Indeed, the unrealistically large magnetic field needed to realize the AB effect in molecular rings has led to a widespread belief that molecular conduction is insensitive to laboratory realizable fields.Herewerevisitthisissue,presentingconditions under which magnetic field control of molecular ring conduc- tion is realizable with pronounced effects on the IV characteristics.We findtheseconditionstobe(a)weakmolecule-leadcoupling,implyingrelativelydistinctconductionresonances, (b)asymmetricjunctionstructure(e.g.,meta-orortho-connectedbenzeneratherthanaparastructure),and(c)minimaldephasing (implying low temperature) so as to maintain coherence between multiple pathways of conduction.