Theoretical investigations of sandwich molecular clusters and nanowires, and their surface assembly

Abstract

Current theoretical studies on one-dimensional infinite sandwich molecular wires (SMWs) predict interesting electronic and magnetic properties, which include half metallicity, high spin filter efficiency, negative differential resistance effects and the ability to function as magnetic on/off molecular switches. However, adsorption of these SMWs on substrates proves to be challenging as these SMWs contain mainly inert hydrocarbon rings. In this work, the structural, electronic and magnetic properties of SMWs containing first row transition metals, boron and silicon heterocycles are studied theoretically. The vanadium boratabenzene SMW is predicted to be a ferromagnetic conductive nanowire and SMWs containing silacyclopentadienyl ring ligands with four transition metals from the 3d series are explored. Theoretical findings reveal a trend of switching from being a conductive wire to semiconducting as the transition metals are varied. Finally, the assembly of two silacyclopentadienyl SMWs are investigated on a semiconducting hydrogen passivated Si(100) surface. Selective rows of dangling bonds can be exposed via feedback-controlled lithography. The vanadium silacyclopentadienyl SMW retains its metallic feature after the assembly, while the manganese silacyclopentadienyl SMW changes from being a semiconductor to quasi metallic. The theoretical work on these SMWs offers vast potential opportunities in the design of novel nanowires for future spintronic and nanoelectronic applications.