The electron and spin polarized transport in wide-voltage-ranges through colbaltporphyrin-based molecular junctions

The electron and spin polarized transport properties of Co benzene-porphyrin-benzene (BPB) molecule coupled to gold (Au) nanowires in a wide voltage range (0–3.0 V) are investigated. By successively removing the front-end Au atoms, we construct Au nanowires with different molecule-electrode contact symmetries. Multiple negative differential resistance (NDR) peaks emerge at different bias voltage regions. It is found that the low-voltage NDR effect at 0.4 V can only be found in the junctions with S–Au top bindings. High-bias NDR effects intrinsic to central molecule at 2.8 V are observed in all the six structures. In particular, both the electron and spin polarized current-voltage (I–V) curves depend strongly on the contact configurations between Co-BPB molecule and the Au electrodes. And the top-binding may result in spin dependent transport properties and will be the priority selection in the design of molecular devices.