Bias‐driven super‐insulating state in prismane single‐molecule contacts

Quantum transport in a single‐molecule contact made of a prismane cluster C 8 attached to quasi‐one‐dimensional gold (100) electrodes is calculated using the ab initio methodology based on the density‐functional theory and the nonequilibrium Green's functions formalism. Varying the junction length L we calculate the length dependence of the zero‐bias conductance G ( L ) and, for a set of the interelectrode distances, the current–voltage ( I – V ) characteristics. It is shown that the G ( L ) dependence is strongly nonmonotonic with a sharp dip at some value of L . With increase in L , the I – V curves change their shape from monotonic curves to curves with a negative differential resistance area and, for a larger L , the junction exhibits the super‐insulating state , i.e., within some applied bias voltage range the current through the junctions is about two orders of magnitude less than the current outside this bias range. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)