Charge-transfer-based mechanism for half-metallicity and ferromagnetism in one-dimensional organometallic sandwich molecular wires.

We present a systematic theoretical study on the mechanism of half-metallicity and ferromagnetism for one-dimensional (1-D) sandwich molecular wires (SMWs) constructed with altering cyclopentadienyl (Cp) and first-row transition metal (Mt). It is unveiled for the first time that, in (MtCp) infinity, one valence electron would transfer from the Mt to the Cp ring, forming Cp (-) and Mt (+) altering structures. This electron transfer not only makes them more stable than the benzene analogues (MtBz) infinity but also leads to completely different half-metallic and ferromagnetic mechanisms. We analyze such unusual half-metallicity and ferromagnetic behaviors and explain each SMW magnetic moment quantitatively. Finally, we indicate that a Peierls transition does not occur in these 1-D SMWs.